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PLATE  I 


MARS 

SINUS  TITANUM 
NOVEMBER,  1894 


I,OWHLL  OBSERVATORY 
Flagstaff,  A.  T.  1894 


TO 

PROFESSOR  WILLIAM  EDWARD  STORY 

SOMETIME  AT   FLAGSTAFF  HIMSELF 

THIS  NEWS   FROM  A  NEIGHBOR 

IS  INSCRIBED 


PREFACE 

THIS  book  is  the  result  of  a  special  study  of 
the  planet  made  during  the  last  opposition,  at 
an  observatory  put  up  for  the  purpose  of  get- 
ting as  good  air  as  practicable,  at  Flagstaff, 
Arizona.  A  steady  atmosphere  is  essential  to 
the  study  of  planetary  detail :  size  of  instru- 
ment being  a  very  secondary  matter.  A  large 
instrument  in  poor  air  will  not  begin  to  show 
what  a  smaller  one  in  good  air  will.  When  this 
is  recognized,  as  it  eventually  will  be,  it  will  be- 
come the  fashion  to  put  up  observatories  where 
they  may  see  rather  than  be  seen. 

Next  to  atmosphere  comes  systematic  study. 
Of  the  extent  to  which  this  was  realized  at 
Flagstaff,  I  need  only  say  that  the  planet  was 
observed  there  from  May  24,  1894,  to  April  3, 
1895,  during  which  time,  to  mention  nothing 
else,  917  drawings  and  sketches  were  made  of 
it.  Prof.  W.  H.  Pickering  and  Mr.  A.  E. 


vi  PREFACE 

Douglass  were  associated  with  me  in  the   ob- 
servations herein  described. 

Such  as  care  to  see  the  original  data  more 
technically  and  minutely  treated  will  find  them 
in  the  first  volume  of  the  Annals  of  this  obser- 
vatory. 

LOWELL  OBSERVATORY, 

November,  1895. 


CONTENTS 


I.  GENERAL  CHARACTERISTICS 1 

1.  As  a  Star 1 

2.  Orbit 8 

3.  Size  and  Shape 14 

II.  ATMOSPHERE 31 

1.  Evidence  of  it 31 

2.  Clouds 60 

III.  WATEB 76 

1.  The  Polar  Cap 76 

2.  Areography 92 

3.  Seas 107 

IV.  CANALS 129 

y  1.    First  Appearances 129 

2.  Map  and  Catalogue 141 

3.  Artificiality 148 

_   4.     Development 154 

V.  OASES 176 

1.  Spots  in  the  Light  Regions ....  176 

2.  Double  Canals 188 

3.  Spots  in  the  Dark  Regions  ....  197 

VI.  CONCLUSION 201 

APPENDIX 213 

INDEX .223 


LIST   OF   ILLUSTRATIONS 

PLATE  PAOB 

I.   MARS,  SINUS  TITANUM      .       Colored  Frontispiece. 
November,  1894.  (P.  L.) 

ORBITS  OF  MARS  AND  THE  EARTH       .        .        .11 
HUYGHENS'  DRAWING  OF  THE  SYRTIS  MAJOR    .    21 
November  28,  1659. 

(From  Flammarion's  "  La  Planete  Mars") 

TERMINATOR  EFFECTS 38 

(P.  i.) 

II.  MAP  OF  THE  SOUTH  POLE  OF  MARS     .        .        .84 
Showing  the  Polar  Cap  and  its  Changes  in  1894. 

(P.  L.) 

III.  MARS,  LONGITUDE  0°  ON  THE  MERIDIAN       .        .    96 

(P.  Z.) 

IV.  MARS,  LONGITUDE  30°  ON  THE  MERIDIAN      .        .    97 

(P.  L.) 
V.   MARS,  LONGITUDE  60°  ON  THE  MERIDIAN      .        .    99 

(P.  L.-) 
VI.  MARS,  LONGITUDE  90°  ON  THE  MERIDIAN      .        .  100 

(P.  Z.) 
VII.   MARS,  LONGITUDE  120°  ON  THE  MERIDIAN     .          101 

(P.  L.) 
VIII.   MARS,  LONGITUDE  150°  ON  THE  MERIDIAN    .        .  102 

(P.  £.) 
IX.   MARS,  LONGITUDE  180°  ON  THE  MERIDIAN    .        .  103 

(P.  L.) 
X.   MARS,  LONGITUDE  210°  ON  THE  MERIDIAN    .        .  104 

(P.  L.) 

XI.  MARS,  LONGITUDE  240°  ON  THE  MERIDIAN    .        .  105 

(P.  Z.) 


x  LIST  OF  ILLUSTRATIONS 

XII.   MARS,  LONGITUDE  270°  ON  THE  MERIDIAN    .        .  105 

(P.  Z.) 

XIII.  MARS,  LONGITUDE  300°  ON  THE  MERIDIAN   .        .  106 

(P.  L.) 

XIV.  MARS,  LONGITUDE  330°  ON  THE  MERIDIAN    .        .  107 

(P.  Z.) 

XV.   SYRTIS  MAJOR Ill 

Showing  Seasonal  Change  during  1894.     (P.  Z.) 

XVI.  HESPERIA 116 

Showing  Seasonal  Change  during  1894.      (P.  Z.) 

XVII.   SEA  OF  THE  SIRENS 122 

Showing  Seasonal  Change  during  1894.      (P.  Z.) 

XVIII.  FASTIGIUM  ARYN 138 

October,  1894.  (P.  Z.) 

XIX.   LACUS  PHOENICIS 162 

November,  1894.  (P.  Z.) 

XX.   TERMINATOR  VIEWS 170 

August  24,  1894.  (  W.  H.  P.) 

XXI.   DRAWINGS  AFTER  OPPOSITION  (EXCEPT  ONE)        .  171 

(A.  E.  D.) 

XXII.   DRAWINGS  AFTER  OPPOSITION       ....  173 

(A.  E.  D.) 

XXIII.  PHISON  AND  EUPHRATES 194 

Both  Double,  November  18,  1894.  (P.  Z.) 

XXIV.  MARS,  ON  MERCATOR'S  PROJECTION      .        .        .218 

(P.  Z.) 
XXV.   DRAWINGS  OF  THE  PLANET  IN  1894       .  .  202 

(P.  Z.) 

XXVI.  DRAWINGS  OF  THE  PLANET  IN  1894       .        .        .208 

(P.  Z.) 


MARS 


i 

GENERAL  CHARACTERISTICS 
I.    AS   A   STAR 

ONCE  in  about  every  fifteen  years  a  startling 
visitant  makes  his  appearance  upon  our  mid- 
night skies,  —  a  great  red  star  that  rises  at  sun- 
set through  the  haze  about  the  eastern  horizon, 
and  then,  mounting  higher  with  the  deepening 
night,  blazes  forth  against  the  dark  background 
of  space  with  a  splendor  that  outshines  Sirius 
and  rivals  the  giant  Jupiter  himself.  Startling 
for  its  size,  the  stranger  looks  the  more  fateful 
for  being  a  fiery  red.  Small  wonder  that  by 
many  folk  it  is  taken  for  a  portent.  Certainly, 
no  one  who  had  not  followed  in  their  courses 
what  the  Greeks  so  picturesquely  called  "the 
wanderers"  (ol  nhavyrai)  would  recognize  in 
the  apparition  an  orderly  member  of  our  own 
solar  family.  Nevertheless,  one  of  the  wander- 
ers it  is,  for  that  star  is  the  planet  Mars,  large 
because  for  the  moment  near,  having  in  due 
course  again  been  overtaken  by  the  Earth,  in 


2  MARS 

her  swifter  circling  about  the  Sun,  at  that  point 
in  space  where  his  orbit  and  hers  make  their 
closest  approach. 

Although  the  apparent  new-comer  is  neither 
new  nor  intrinsically  great,  he  possesses  for  us 
an  interest  out  of  all  proportion  to  his  size  or 
his  relative  importance  in  the  universe ;  and 
this  for  two  reasons  :  first,  because  he  is  of  our 
own  cosmic  kin ;  and  secondly,  because  no  other 
heavenly  body,  Venus  and  the  Moon  alone  ex- 
cepted,  ever  approaches  us  so  near.  What  is 
more,  we  see  him  at  such  times  better  than  we 
ever  do  Venus,  for  the  latter,  contrary  to  what 
her  name  might  lead  one  to  expect,  keeps  her- 
self so  constantly  cloaked  in  cloud  that  we  are 
permitted  only  the  most  meagre  peeps  at  her 
actual  surface ;  while  Mars,  on  the  other  hand, 
lets  us  see  him  as  he  is,  no  cloud-veil  of  his,  as 
a  rule,  hiding  him  from  view.  He  thus  offers 
us  effective  opportunities  for  study  at  closer 
range  than  does  any  other  body  in  the  uni- 
verse except  the  Moon.  And  the  Moon  balks 
inquiry  at  the  outset.  For  that  body,  from 
which  we  might  hope  to  learn  much,  appears 
upon  inspection  to  be,  cosmically  speaking, 
dead.  Upon  her  silent  surface  next  to  nothing 
now  takes  place  save ( for  the  possible  crumbling 
in  of  a  crater  wall.  jFor  all  practical  purposes 
Mars  is  our  nearest  neighbor  in  space.  Of  all 
the  orbs  about  us,  therefore,  he  holds  out  most 


AS  A  STAR  3 

promise  of  response  to  that  question  which  man 
instinctively  makes  as  he  gazes  up  at  the  stars : 
What  goes  on  upon  all  those  distant  globes  ? 
Are  they  worlds,  or  are  they  mere  masses  of 
matter  ?  Are  physical  forces  alone  at  work 
there,  or  has  evolution  begotten  something 
more  complex,  something  not  unakin  to  what 
we  know  on  Earth  as  life  I  It  is  in  this  that 
lies  the  peculiar  interest  of  Mars. 

That  just  as  there  are  other  masses  of  matter 
than  our  globe,  so  there  are  among  them  other 
worlds  than  ours  is  an  instant  and  inevitable 
inference  from  what  we  see  about  us.  That  we 
are  the  only  part  of  the  cosmos  possessing  what 
we  are  pleased  to  call  mind  is  so  earth-centred 
a  supposition,  that  it  recalls  the  other  earth- 
centred  view  once  so  devoutly  held,  that  our 
little  globe  was  the  point  about  which  the 
whole  company  of  heaven  was  good  enough 
to  turn.  Indeed,  there  was  much  more  reason 
to  think  that  then,  than  to  think  this  now,  for 
there  was  at  least  the  appearance  of  turning, 
whereas  there  is  no  indication  that  we  are  sole 
denizens  of  all  we  survey,  and  every  inference 
that  we  are  not. 

That  we  are  in  some  wise  kin  to  all  the  rest 
of  the  cosmos,  science  has  been  steadily  demon- 
strating more  and  more  clearly.  The  essential 
oneness  of  the  universe  is  the  goal  to  which  all 
learning  tends.  Just  as  Newton  proved  all  the 


4  MARS 

planets  to  obey  a  common  force,  the  Sun  ;  just 
as  Laplace  showed  it  to  be  probable  that  we 
were  all  evolved  from  one  and  the  same  primal 
nebula ;  so  more  recently  the  spectroscope  has 
revealed  unsuspected  relationship  betwixt  us 
and  the  stars.  Matter  turns  out  to  be  but  com- 
mon property;  and  the  very  same  substances 
with  which  we  are  so  familiar  on  the  Earth,  iron, 
magnesium,  sodium,  and  so  forth,  prove  present 
on  those  far-off  suns  that  strew  the  depths  of 
space.  Only  in  detail  does  everything  differ. 

So.  much  for  matter.  As  for  that  manifesta- 
tion of  it  known  as  mind,  modesty,  if  not  intel- 
ligence, forbids  the  thought  that  we  are  sole 
thinkers  in  all  we  see.  Indeed,  we  seldom  stop 
in  our  locally  engrossing  pursuits  to  realize  how 
small  the  part  we  play  in  the  universal  drama. 
Let  us  consider  for  a  moment  how  we  should 
appear,  or,  more  exactly,  not  appear,  could  we 
get  off  our  world  and  scan  it  from  without.  If 
distance  could  thus  reduce  for  us  the  scale  upon 
which  the  universe  is  fashioned  to  one  we  could 
take  in,  that  on  which  the  Earth  should  be  rep- 
resented by  a  good-sized  pea,  with  a  grain  of 
mustard  seed,  the  Moon,  circling  about  it  at  a 
distance  of  seven  inches,  the  Sun  would  be  a 
globe  two  feet  in  diameter,  two  hundred  and 
fifteen  feet  away.  Mars,  a  much  smaller  pea, 
would  circle  around  the  two-foot  globe  three 
hundred  and  twenty-five  feet  from  its  surface  ; 


AS  A  STAR  5 

Jupiter,  an  orange,  at  a  distance  of  a  fifth  of  a 
mile;  Saturn,  a  small  orange,  at  two  fifths  of 
a  mile  ;  and  Uranus  and  Neptune,  good-sized 
plums,  three  quarters  of  a  mile  and  a  mile  and 
a  quarter  away,  respectively.  On  this  same 
scale  the  nearest  star  would  lie  eight  thousand 
miles  off,  and  an  average  third-magnitude  star 
at  about  the  present  distance  of  our  Moon ;  that 
is,  on  a  scale  upon  which  the  Moon  should  be 
but  seven  inches  off,  the  average  star  would 
still  be  as  far  from  us  as  the  Moon  is  now. 
Now  when  we  think  that  each  of  these  stars 
is  probably  the  centre  of  a  solar  system  grander 
than  our  own,  we  cannot  seriously  take  our- 
selves to  be  the  only  minds  in  it  all. 

Probable,  however,  as  extra-terrestrial  life  in 
general  is,  it  is  another  matter  to  predicate  it 
in  any  particular  case.  Nevertheless,  if  it  exist 
it  must  exist  somewhere,  and  the  first  place  to 
scan  is  the  place  we  can  scan  best.  Now  the 
Moon  appears  to  be  hopelessly  dead.  Mars, 
therefore,  becomes  of  peculiar  interest,  and  it 
was  in  hope  of  learning  something  on  the  sub- 
ject that  the  observations  about  to  be  described 
in  this  book  were  made.  Before  proceeding, 
however,  to  an  account  of  what  in  consequence 
we  have  learned  about  our  neighbor,  a  couple 
of  misapprehensions  upon  the  subject,  —  not 
confined,  I  am  sorry  to  say,  wholly  to  the  lay 
mind,  —  must  first  be  corrected.  One  of  these  is 


6  MARS 

that  extra-terrestrial  life  means  extra-terrestrial 
human  life.  Such  an  inference  recalls  to  my 
mind  the  exclamation  of  an  innocent  globe- 
trotter to  a  friend  of  mine  in  Japan  once,  a 
connoisseur  of  Japanese  painting,  upon  being 
told  that  the  Japanese  pictures  were  exceed- 
ingly fine.  "What!"  the  globe-trotter  ex- 
claimed in  surprise,  "  do  the  Japanese  have  pic- 
tures,—  real  pictures,  I  mean,  in  gilt  frames?" 
The  existence  of  extra-terrestrial  life  does  not 
involve  "real  life  in  trousers,"  or  any  other 
particular  form  of  it  with  which  we  are  locally 
conversant.  Under  changed  conditions,  life  it- 
self must  take  on  other  forms. 

The  next  point  is  as  to  what  constitutes 
proof.  Now,  between  the  truths  we  take  for 
granted  because  of  their  age,  and  those  we 
question  because  of  their  youth,  we  are  apt  to 
forget  that  in  both  proof  is  nothing  but  prepon- 
derance of  probability.  The  law  of  gravitation, 
for  example,  than  which  we  believe  nothing  to 
be  more  true,  depends  eventually,  as  recognized 
by  us,  upon  a  question  of  probability ;  and  so 
do  the  thousand  and  one  problems  of  daily  life 
upon  so  many  of  which  we  act  unhesitatingly 
and  should  be  philosophic  fools  if  we  did  not. 
All  deduction  rests  ultimately  upon  the  data 
derived  from  experience.  This  is  the  tortoise 
that  supports  our  conception  of  the  cosmos. 
For  us,  therefore,  the  point  at  issue  in  any 


AS  A  STAR  7 

theory  is  not  whether  there  be  a  possibility  of 
its  being  false,  but  whether  there  be  a  proba- 
bility of  its  being  true.  This,  which  is  evident 
enough  when  squarely  envisaged,  is  too  often 
lost  sight  of  in  discussing  theories  on  their  road 
to  recognition.  Negative  evidence  is  no  evi- 
dence at  all,  and  the  possibility  that  a  thing 
might  be  otherwise,  no  proof  whatever  that  it 
is  not  so.  The  test  of  a  theory  is,  first,  that  it 
shall  not  be  directly  contradicted  by  any  facts, 
and  secondly,  that  the  probabilities  in  its  favor 
shall  be  sufficiently  great. 

As  to  what  constitutes  sufficiency  it  is  impor- 
tant to  bear  in  mind  one  point,  namely,  that  the 
odds  that  a  thing  is  true  from  the  fact  that  two 
or  more  witnesses  agree  on  the  same  statement 
is  not  the  sum  of  the  odds  that  each  tells  the 
truth,  but  the  product  of  those  odds.1  There- 
fore, if  the  chances  for  the  truth  of  a  theory,  in 
consequence  of  its  explaining  a  certain  set  of 
details,  be  three  to  one,  and  because  of  its  ex- 
plaining another  set,  —  for  the  purposes  of  argu- 
ment unrelated  to  the  first,  —  four  to  one,  then 
the  chances  in  its  favor  from  its  explaining  both 
sets  are  not  seven  to  one  but  twelve  to  one.  If 
it  explains  a  third  set  whose  independently  re- 
sulting odds  are  of  five  to  one,  the  chances  in 
its  favor  become,  from  its  explaining  all  three 
sets,  not  twelve  to  one  but  sixty  to  one ;  if  a 
fourth  set  be  added,  with  further  odds  of  five  to 

1  See  Lacroix,  Traite  Elemental™  des  Probabilites,  p.  220. 


8  MAES 

one,  the  sum  total  from  the  four  becomes  not 
seventeen  to  one  but  three  hundred  to  one  in 
favor  of  its  being  true.  It  will  be  seen  how 
rapidly  the  probability  of  the  truth  of  a  theory 
mounts  up  from  the  amount  of  detail  it  explains. 
This  law  is  to  be  remembered  throughout  the 
coming  exposition,  for  whatever  the  cogency 
of  each  detail  of  the  argument  in  itself,  the 
concurrence  of  all  renders  them  not  simply 
additionally  but  multiplicity  effective.  That 
different  lines  of  induction  all  converge  to  one 
point  proves  that  point  to  be  the  radiant  point 
of  the  result. 

II.     ORBIT 

To  determine  whether  a  planet  be  the  abode 
of  life  in  the  least  resembling  that  with  which 
we  are  acquainted,  two  questions  about  it  must 
be  answered  in  turn :  first,  are  its  physical  con- 
ditions such  as  render  it,  in  our  general  sense, 
habitable  ;  and  secondly,  are  there  any  signs  of 
its  actual  habitation  ?  These  problems  must  be 
attacked  in  their  order,  for  unless  we  can 
answer  the  first  satisfactorily,  it  were  largely 
futile  to  seek  for  evidence  of  the  second. 

Thoroughly  to  appreciate,  then,  the  physical 
condition  of  Mars,  we  must  begin  at  the  begin- 
ning of  our  knowledge  of  the  planet,  since  every 
detail  will  be  found  to  play  its  part  in  the  final 
result.  I  shall  therefore  give  in  a  word  or  two 


ORBIT  9 

the  general  facts  known  about  the  planet,  before 
taking  up  the  observations  which  make  the  sub- 
ject matter  of  this  book.  The  first  of  these 
general  facts  is  the  path  the  planet  describes 
about  the  Sun.  Who  first  found  out  that  the 
ruddy  star  we  call  Mars  was  not  like  the  rest  of 
the  company  about  him  we  do  not  know  ;  possi- 
bly some,  to  fame  unknown,  Chaldean  shepherd 
alone  with  the  night  upon  the  great  Chaldean 
plains.  With  the  stars  for  sole  companions 
while  his  sheep  slept,  he  must,  as  he  watched 
them  night  after  night,  have  early  recognized 
that  they  always  kept  the  same  configuration. 
They  rose  and  set,  but  they  all  rose  and  set  to- 
gether. But  one  night  he  thought  he  noticed 
that  one  of  them  had  changed  its  place  with 
reference  to  the  rest.  A  few  nights  later  he 
became  sure  of  it.  One  of  the  immovable  had 
patently  moved.  That  memorable  though  un- 
remernbered  night  marked  the  birth  of  our 
acquaintance  with  the  rest  of  the  universe. 

Whether  the  midnight  pioneer  was  Chaldean 
or  Assyrian  or  of  some  other  race,  certain  it 
is  that  to  the  Egyptians  we  owe  the  first  sys- 
tematic study  of  the  motions  of  this  and  of  four 
other  roving  stars,  and  to  the  Greeks  whom  they 
taught,  the  name  by  which  we  know  them,  that 
of  planets,  meaning  merely  wanderers.  Since 
then,  as  we  know,  many  others  of  like  habit 
have  been  added  to  the  list. 


10  MARS 

Now,  from  observations  of  the  apparent  places 
of  a  planet,  it  is  possible  to  determine  the  rela- 
tive path  of  the  planet  in  space  as  compared 
with  the  path  of  the  Earth.  This  Kepler  did 
from  observations  of  Tycho  Brahe's,  and  showed 
the  wanderers  to  belong  to  a  system  of  bodies, 
all  revolving  about  the  Sun  in  various  elliptic 
orbits,  the  Sun  being  at  the  focus  of  each  ellipse. 
He  also  found  that  the  line  connecting  each 
planet  with  the  Sun  passed  over  equal  areas  in 
equal  times,  and  thirdly,  that  the  squares  of 
the  times  were  as  the  cubes  of  the  major  axes 
of  the  orbits.  From  these  three  "laws"  New- 
ton deduced  the  fact  that  the  force  controlling 
the  planets  was  directed  toward  the  Sun,  that 
it  varied  inversely  as  the  square  of  the  distance, 
and  that  it  was  the  same  in  origin  for  all.  This 
is  the  so-called  law  of  gravitation,  and  this  is 
the  way  in  which  it  was  discovered.  We  do 
not  yet  know  why  gravity  so  acts,  but  it  is  in- 
teresting to  note  that  it  follows  the  simple  law 
of  geometrical  expansion,  diminishing  in  exact 
ratio  to  the  space  it  fills,  just  like  electricity  or 
light.  It  may,  therefore,  also  be  a  wave  mo- 
tion. 

Thus  all  the  wanderers  proved  to  be  asso- 
ciated in  common  dependence  on  the  Sun,  and 
among  the  members  of  the  solar  family  thus 
recognized  Mars  was  found  to  hold  the  position 
next  exterior  to  the  Earth,  and  the  path  he  fol- 


ORBIT 


11 


lowed  in  his  circuit  of  the  Sun  to  be  situated 
with  regard  to  the  Earth's  as  in  the  following 
diagram. 


(Autumnal  Equinox  of  MARS 
uthern  Hemisphere 


154° 
Aphelion  y 


•Winter 

Solstice  of 

MARS 
Southern 
Hemisphere 


&pt. 


Nov.1.1894 
Ot.JO.1894. 


fSept.1,1894 


MARS 

Southern 

r  Hemisphere 


Aug.4y 


'Aug^.mS 
'June  1,1894 
Vernal  Equinox  of   MARS  Southern  Hemisphere 

Diagram  of  the  Orbits  of  Mare  and  the  Earth. 

On  consulting  the  diagram  we  shall  at  once 
perceive  why  it  is  that  every  fifteen  years  Mars 
becomes  so  unusually  bright  as  to  seem,  to  one 
who  has  not  kept  track  of  him,  a  new  and  start- 
ling star.  His  orbit,  it  will  be  seen,  is  an  ellipse 
of  some  eccentricity,  and  deviates  in  conse- 
quence considerably  from  a  circle.  The  point 
marked  Perihelion  denotes  the  point  where  the 
planet  is  nearest  the  Sun ;  the  point  marked 


12  MARS 

Aphelion,  the  point  where  the  planet  is  the 
most  remote  from  the  Sun.  In  like  manner 
the  points  marked  Perihelion  and  Aphelion  on 
the  inner  circle  show  the  corresponding  points 
of  the  Earth's  orbit,  which  is  much  more  nearly 
circular.  Now  as  the  two  planets  revolve  in 
different  periods  of  time,  Mars  taking  686.98  of 
our  days  to  complete  his  circuit,  and  the  Earth 
365.26  days  to  complete  hers,  the  one  planet 
will  overtake  the  other  only  once  every  two 
years  and  two  months  or  so.  Meanwhile  they 
are  at  great  distances  apart.  But  even  when 
they  do  meet,  they  do  not  always  meet  equally 
near.  For  the  one  orbital  period  is  not  an  ex- 
act multiple  of  the  other,  and  as  the  orbits  are 
both  ellipses,  it  is  evident  that  these  meetings 
of  the  two  planets  will  occur  at  different  points 
of  their  orbits,  and,  therefore,  at  different  dis- 
tances. If  the  meeting  occur  when  Mars  is  in 
perihelion  the  planets  approach  one  another 
within  35,050,000  miles ;  if  in  aphelion,  only 
within  61,000,000  miles. 

But  even  this  difference  in  distance  does  not 
measure  the  full  extent  of  the  variation  in  bril- 
liancy. As  the  brightness  of  an  illuminated 
body  varies  inversely  as  the  square  of  its  dis- 
tance from  the  source  of  light,  and  as  the  total 
amount  of  light  it  reflects  to  fin  observer  varies 
inversely  as  the  square  of  his  distance  from  it, 
it  makes  every  difference  in  the  apparent  bril- 


ORBIT  13 

liancy  of  a  body  how  the  body  is  situated,  both 
with  regard  to  the  source  of  light  and  with 
regard  to  the  observer.  Now  it  so  chances  that 
at  the  meetings  of  Mars  with  the  Earth  these 
two  factors  attain  their  maximum  effects  nearly 
together,  and  similarly  with  their  minimum. 
For  at  the  times  when  we  are  closest  to  Mars, 
Mars  is  nearly  at  his  closest  to  the  Sun,  and 
reversely  when  we  meet  him  at  the  opposite 
part  of  his  orbit.  It  thus  comes  about  that  at 
some  meetings,  —  oppositions,  they  are  called, 
because  Mars  then  is  in  the  opposite  part  of  the 
sky  from  the  Sun,  —  the  planet  appears  four 
and  one  half  times  as  bright  as  at  others.  Here, 
then,  we  have  the  explanation  of  the  planet's 
great  changes  in  appearance,  changes  so  great 
as  to  deceive  any  one  who  has  not  followed  its 
wanderings,  into  the  belief  that  it  is  some  new 
and  portentous  apparition. 

Important  as  is  the  ellipse  in  which  Mars 
moves  with  regard  to  his  visibility  by  us,  it 
is  considerably  more  important  as  regards  the 
physical  condition  of  the  planet  itself.  For  the 
Sun  being  situated  at  one  of  the  foci  of  his 
orbit,  the  motion  of  the  planet  sweeps  him  now 
near  to,  now  far  from  that  dispenser  of  light 
and  warmth ;  and  the  amount  of  both  which 
the  planet  receives  varies  just  like  gravity 
with  his  distance  from  their  source.  Now  the 
eccentricity  of  the  orbit  of  Mars  is  such  that 


14  MARS 

when  nearest  the  Sun  his  distance  is  129,- 
500,000  miles,  when  at  his  mean  distance 
141,500,000  miles,  and  when  most  remote 
154,500,000  miles.  The  proportion  of  light 
and  heat  he  receives  respectively  is  therefore 
roughly  as  16  to  20  to  24;  or  half  as  much 
again  at  certain  times  as  at  others. 

So  much  in  our  knowledge  of  Mars  is  pre- 
telescopic.  Men  might  have  and  practically 
did  learn  this  much  without  ever  seeing  the 
planet  other  than  as  a  point  of  light.  Its  orbit 
was  tolerably  accurately  known  and  could  have 
been  known  still  more  accurately  without  tele- 
scopic aid  ;  not  so,  until  we  become  much  more 
nearly  omniscient  than  we  at  present  are,  the 
planet's  self. 

III.     SIZE   AND   SHAPE 

With  the  telescope  we  enter  upon  a  new 
phase  in  our  knowledge  of  the  planet :  the  de- 
termination of  its  shape  and  size. 

The  relative  plan  of  the  solar  system  can  be 
learned  with  great  accuracy  from  observations 
of  the  motions  of  its  members;  not  so  easily 
learned  is  the  scale  upon  which  it  is  con- 
structed. Although  the  former  is  intrinsically 
a  very  complicated,  the  latter  a  very  simple 
problem,  two  characteristics  of  the  actual  sys- 
tem make  it  possible  to  solve  the  former  much 
more  nearly  than  the  latter.  One  of  these 


SIZE   AND    SHAPE  15 

characteristics  is  the  fact  that  the  distances 
between  the  masses  which  compose  the  system 
are  very  much  greater  than  the  dimensions  of 
the  masses  themselves,  of  quite  a  higher  order 
of  magnitude.  The  diameters  of  the  planets 
are  measured  by  thousands  of  miles,  the  dis- 
tances between  them  by  tens  of  millions.  The 
second  characteristic  consists  in  the  approxi- 
mately spherical  shape  of  the  planets  them- 
selves, and  in  the  fact  that  by  a  mathematical 
consequence  of  the  actual  law  of  gravitation  a 
sphere  acts  upon  any  outside  body  as  if  all  its 
mass  were  concentrated  at  its  centre,  a  most 
interesting  peculiarity  not  true  under  many 
other  supposable  laws.  These  two  facts  very 
materially  simplify  the  problem  of  the  motions 
of  celestial  mechanics. 

But  just  as  the  first  of  these  peculiarities 
helps  us  to  comprehension  of  the  relative  di- 
mensions of  the  solar  system,  so  does  it  hinder 
us  in  determining  its  actual  dimensions.  For 
this  determination  depends  upon  a  problem  in 
celestial  surveying,  the  finding  the  distance  to 
a  body  by  measuring  the  angle  it  subtends  from 
the  two  ends  of  a  base-line.  Now,  as  unfortu- 
nately we  cannot  get  off  the  earth  for  the  pur- 
pose, our  base-line  is  at  most  the  diameter  of 
the  earth  itself,  and  as  the  distance  to  the  other 
body  immensely  exceeds  our  own  size,  the  angle 
to  be  measured  becomes  so  excessively  small  as 


16  MARS 

to  be  very  difficult  to  determine  with  accuracy. 
Fortunately  this  is  matter  chiefly  of  theoretic 
regret,  as  we  now  know  the  actual  sizes  to 
within  a  degree  ©f  exactness  practically  suffi- 
cient for  most  purposes  but  perturbations;  to 
within  about  ^  part  of  the  whole,  so  far  as 
our  ultimate  measure  is  concerned,  the  distance 
we  are  off  from  the  Sun. 

A  good  idea  of  the  method  and  some  appre- 
ciation of  the  difficulty  involved  in  it  can  be 
got  by  considering  a  precisely  similar  case,  that 
of  determining  the  distance  of  a  spire  a  mile 
and  three  fifths  away  by  shutting  first  one  eye 
and  then  the  other  and  noting  the  shift  of  the 
spire  against  its  background.  It  is  needless 
to  add  that  without  telescopic  aid  the  deter- 
mination is  impossible,  and  that  it  is  exceeding 
difficult  with  it. 

Nevertheless,  from  the  distance  of  the  Sun 
determined  in  this  manner,  we  find  from 
measurements  of  the  apparent  disk  of  the 
planet  made  at  Flagstaff  that  Mars  is  about 
4,215  miles  in  diameter.  This  makes  his  sur- 
face a  little  more  than  a  quarter  that  of  the 
Earth  and  his  volume  about  one  seventh  of 
hers. 

The  next  point  to  find  out  is  his  mass,  that 
is,  the  amount  of  matter  he  contains.  This  is 
very  easy  to  determine  when  a  planet  has  a 
satellite,  and  very  difficult  to  determine  when 


SIZE  AND  SHAPE  17 

a  planet  has  not.  The  reason  is  this :  the  mass 
of  a  body  is  known  from  the  pull  it  exerts, 
inasmuch  as  this  pull  depends,  by  the  law  of 
gravitation,  upon  its  mass  and  the  square  of 
its  distance.  If  then  we  know  the  pull  and 
the  distance  from  which  it  is  exerted,  we  can 
find  the  mass.  J  Now  we  gauge  the  pull  from 
its  effects  in  causing  some  other  body  to  move. 
By  measuring,  therefore,  the  motion  of  this 
other  body,  we  learn  the  mass  of  the  first  one. 
To  get  this  accurately  the  motion  must  be  large 
enough  to  admit  of  satisfactory  measurement  in 
the  first  place,  and  be  as  uncomplicated  with 
motions  due  to  pulls  of  other  bodies  as  pos- 
sible, in  the  second.  As  each  body  pulls  every 
other,  and  it  is  only  their  relative  displacement 
we  can  measure,  as  we  have  no  foothold  in 
space,  even  the  case  of  only  two  bodies  pre- 
sents difficulties  of  apportionment.  We  can 
learn  the  aggregate  mass  of  the  two,  but  not 
the  separate  mass  of  either  alone  unless  it  so 
happen  that  the  mass  of  one  is  so  insignificant 
compared  with  the  other  that  the  mass  of  that 
other  may  be  taken  as  the  mass  of  both.  Now 
this  is  substantially  realized  in  the  case  of  the 
solar  system.  Owing  to  the  greatly  dispropor- 
tionate size  of  primary  and  secondary  bodies  in 
it,  the  great  size  of  the  Sun  as  compared  with 
that  of  any  of  the  planets,  and  the  great  size 
of  the  planets  as  compared  with  their  satellites 


18  MARS 

(with  the  exception  of  the  Moon,  and  she,  for- 
tunately,  is  an  only  child),  the  determination  of 
the  mass  of  the  smaller  by  measurement  of  its 
motion  about  the  larger,  —  as  if  only  the  pair 
of  bodies  under  consideration  existed,  and  the 
mass  of  both  were  concentrated  in  the  greater 
of  the  two,  —  is  very  nearly  exact.  In  conse- 
quence each  planet  discloses  with  some  accu- 
racy the  mass  of  the  Sun,  but  tells  next  to 
nothing  about  its  own  mass;  and  in  the  same 
way  each  satellite  reveals  the  mass  of  its  pri- 
mary. The  mass  of  a  planet  possessing  a  satel- 
lite is,  therefore,  easy  of  determination.  Not 
so  that  of  one  which  travels  unattended.  The 
only  way  to  obtain  its  mass  is  from  the  pertur- 
bations or  disturbing  pulls  it  exerts  upon  the 
other  planets,  or  upon  stray  comets  from  time 
to  time,  and  these  disturbances  are,  by  the 
nature  of  the  case,  of  a  much  smaller  order  of 
magnitude,  to  say  nothing  of  the  fact  that  all 
act  coincidently  to  increased  difficulty  of  disen- 
tanglement. The  practical  outcome  of  this  in 
the  case  of  Mars  was  that  before  his  satellites 
were  discovered  the  values  obtained  for  his 
mass  ranged  all  the  way  from  syoiWo  to 
2500000  of  the  mass  of  the  Sun,  or,  in  other 
words,  varied  fifty  per  cent.  His  insignificant 
satellites,  however,  and  just  because  they  are 
insignificant,  have  made  it  possible  to  learn  his 
mass  with  great  exactness.  It  turns  out  to 


SIZE  AND  SHAPE  19 

be  swhyiy  of  that  of  the  Sun,  or  JJ  of  that  of 
the  Earth. 

Knowing  his  mass,  we  know  his  average  den- 
sity, since  to_  find  it  we  have  but  to  divide  his 
mass  by  his  volume.  It  proves  to  be  -5%  of 
that  of  the  Earth.  We  also  learn  the  force  of 
gravity  at  his  surface,  inasmuch  as  this  is  di- 
rectly as  his  mass  and  inversely  as  the  square 
of  his  radius.  It  comes  out  -ffQ  of  that  of  the 
Earth.  In  consequence,  all  things  there  would 
weigh  but  -f-fo  of  their  weight  on  earth ;  a  man, 
for  example,  weighing  150  pounds  here  would 
weigh  but  55  pounds  if  transported  to  the  sur- 
face of  Mars,  and  all  manual  labor  would  be 
lightened  threefold. 

So  soon  as  the  planet  was  scanned  telescopi- 
cally,  he  was  seen  to  present  a  disk,  round  at 
times,  at  other  times  lacking  somewhat  of  a 
perfect  circle,  showing  like  the  Moon  when  two 
days  off  from  full.  Such  appearance  visibly 
demonstrated,  first,  that  he  was  not  a  self- 
luminous  body,  and  secondly,  that  he  revolved 
about  the  Sun  outside  of  the  Earth.  A  glance 
at  the  diagram  of  the  orbit  will  make  the  latter 
point  clearer.  If  we  draw  a  line  from  the  Sun 
to  the  centre  of  Mars  and  pass  a  plane  through 
the  planet  perpendicular  to  this  line  and  to  the 
plane  of  his  orbit,  this  plane  will  divide  the 
illumined  half  of  him  from  the  unillumined  half. 
If  now  we  draw  another  line  from  any  point 


20  MARS 

of  the  Earth's  orbit  to  Mars'  centre,  and  pass  a 
plane  similarly  perpendicular  to  that,  it  will  cut 
off  the  hemisphere  we  see  at  any  moment  from 
the  one  we  do  not.  As  the  two  lines  do  not  in 
general  coincide,  it  will  appear  that  in  certain 
positions,  in  fact  in  all  but  two,  Mars  must  pre- 
sent to  us  a  face  partly  steeped  in  daylight, 
partly  shrouded  in  night ;  in  short,  that  he 
shows  gibbous  like  the  Moon  when  she  is  be- 
tween the  half  and  the  full.  This  accounts  for 
the  look  of  the  drawings  made  during  June, 
1894,  in  which  from  a  seventh  to  a  sixth  of 
the  disk  is  wanting  on  the  left.1  By  drawing 
lines  from  his  centre  to  more  than  one  posi- 
tion occupied  by  the  Earth  it  will  be  seen  that 
this  lacking  lune  reaches  a  maximum  when  the 
Earth  as  viewed  from  Mars  is  at  extreme 
elongation  from  the  Sun,  and  that  the  amount 
of  the  phase  at  such  time  exactly  equals  the 
number  of  degrees  of  this  elongation.  For 
example,  on  the  sixteenth  of  last  June  the  lack- 
ing lune  amounted  to  47°,  that  is,  the  Earth 
was  then  evening  star  upon  the  Martian  twi- 
light skies  at  an  angular  distance  of  47°  from 
the  Sun,  about  what  Venus  seems  to  us  at  her 
extreme  elongation.  In  fact,  to  Mars  we  oc- 
cupy much  the  same  astronomical  position  that 
Venus  does  to  us. 

To  Huyghens  we  owe  the  first  really  impor- 
1  Plates  XV.,  XVI.,  XVII. 


SIZE  AND   SHAPE 


21 


Huyghens'  drawing  of  the 
Syrtis  Major,  Nov.  28, 1659, 
7  P.  M.  Reproduced  from 
Flammarion's  "  La  Planete 
Mars." 


tant  telescopic  observation  upon  the  planet    On 
November  28,  1659,  at  7  s 

p.  M.,  he  made  the  first 
drawing  of  the  planet 
worthy  the  name,  for  on 
it  is  the  first  identifiable 
feature  ever  made  out  by 
man  on  the  surface  of 
Mars.  This  feature  is  the 
Hourglass  Sea,  now  more 
commonly  known  as  the 
Syrtis  Major.  The  ac- 
companying cut  of  it  is 
reproduced  from  Flarn- 
marion.  If  the  dark  patch  in  it  be  compared 
with  the  markings  in  the  other  pictures  of  the 
planet,  shown  later  in  this  book,  it  will  be  seen 
that  the  patch  can  be  none  other  than  the 
Hourglass  Sea. 

Now,  innocent  as  it  looks  of  much  detail, 
Huyghens'  drawing  is  perhaps  the  most  im- 
portant one  of  Mars  that  has  ever  been  made. 
For,  from  his  observations  of  the  spot  it  depicts 
at  successive  dates,  he  was  able  to  prove  that 
Mars  rotated  on  his  own  axis,  and  to  determine 
the  time  of  that  rotation,  about  24  hours.  As 
he  subsequently  came  to  doubt  his  results,  the 
honor  of  the  discovery  rests  with  Cassini,  who, 
in  1666,  definitely  determined  that  the  planet 
rotated  in  24  hours  40  minutes.  Thus  was  it 


22  MARS 

first  learned  that  Mars  had  a  day,  and  that  its 
length  was  not  far  from  the  length  of  our  own. 

The  importance  of  these  earliest  pictures  of 
Mars  has  not  lapsed  with  the  lapse  of  time.  By 
comparison  of  this  and  other  early  drawings 
with  modern  ones,  has  been  deduced  a  very 
accurate  value  of  the  length  of  the  Martian 
day  (its  sidereal  day),  a  determination  accurate 
to  the  tenth  of  a  second.  It  amounts  to  24 
hours,  37  minutes,  22.7  seconds.  Our  sidereal 
day,  that  is,  the  day  reckoned  by  the  stars,  not 
by  the  Sun,  is  roughly  23  hours,  56  minutes; 
so  that  the  Martian  day  is  about  40  minutes 
longer  than  our  own.  The  result  is  not  given 
here  closer  than  the  tenth  of  a  second,  because 
the  Flagstaff  observations  have  shown  that  the 
value  of  the  length  of  the  Martian  day  hitherto 
accepted  is  probably  a  trifle  too  small. 

From  the  discovery  of  the  rotation  followed 
the  approximate  position  of  the  planet's  poles. 
Round  about  the  poles  so  determined  appeared 
two  white  patches,  the  first  study  of  which  we 
owe  to  Maraldi.  They  are  the  planet's  polar 
caps.  They  are  to  be  detected  with  the  smallest 
modern  telescope. 

The  apparent  position  of  the  planet  poles  as 
presented  to  the  Earth  gives  the  tilt  of  the 
planet's  axis  to  the  plane  of  its  orbit.  It  turns 
out  to  be  about  25°.  This  is  very  nearly  the 
same  as  the  Earth's  axial  tilt  to  the  plane  of 


SIZE  AND  SHAPE  23 

her  orbit,  which  is  23°  24'.  As  the  inclination 
of  the  axis  to  the  plane  of  the  orbit  determines 
the  seasons,  we  see  that  not  only  has  Mars  its 
spring,  summer,  autumn,  and  winter,  but  that 
these  are  not  very  unlike  our  own. 

It  is  not  uninteresting  to  inquire  in  what  the 
difference  consists.  The  slight  difference  of  tilt 
in  the  Martian  axis  would  slightly  extend  the 
breadth  of  the  tropical  and  the  polar  regions  at 
the  expense  of  the  temperate  ones,  and  thus 
accentuate  the  seasons,  but  the  chief  seasonal 
contrast  between  Mars  and  the  Earth  would 
come  in  in  consequence  of  the  much  greater 
eccentricity  of  Mars'  orbit.  For  the  more  ec- 
centric the  ellipse,  the  greater  the  variation  in 
the  planet's  velocity  at  different  parts  of  it,  in- 
asmuch as  the  Sun  pulls  the  planet  toward  him- 
self with  a  force  depending  on  his  distance. 
The  less  this  distance,  the  greater  the  angular 
velocity.  But  the  angular  velocity  determines 
the  length  of  the  seasons  upon  a  planet  whose 
pole  of  rotation  is  tilted  to  the  plane  of  its 
orbit,  like  the  Earth  or  Mars.  The  greater  the 
eccentricity  of  the  ellipse,  therefore,  the  greater 
the  difference  in  the  length  of  the  seasons.  In 
the  case  of  the  Earth  the  difference  is  about 
eight  days,  winter  in  the  northern  hemisphere 
being  eight  days  shorter  than  summer.  In  the 
case  of  Mars,  owing  to  the  much  greater  eccen- 
tricity of  his  orbit  combined  with  his  longer 


24  MARS 

period,  the  difference  amounts  to  74  days.  In 
one  hemisphere  winter  is  long  and  cold,  sum- 
mer short  and  hot ;  in  the  other  winter  and 
summer  interchange.  Owing  to  the  present 
position  of  the  line  of  apsides,  the  line  connect- 
ing the  points  of  Mars'  nearest  approach  to  and 
farthest  recession  from  the  Sun,  the  former 
hemisphere  happens  to  be  the  southern  one; 
the  latter,  the  northern.  The  lengths  of  their 
respective  seasons  are  as  follows  :  — 

In  the  northern  hemisphere,  winter  lasts  147 
of  his  own  days;  spring,  191  days;  summer, 
181  days ;  autumn,  149  days ;  while  in  the 
southern  hemisphere,  winter  lasts  181  days; 
spring,  149  days;  summer,  147  days;  autumn, 
191  days. 

Curiously  enough,  an  analogous  distribution 
of  heat  and  cold  occurs  also  at  the  present  time 
in  the  case  of  the  Earth ;  its  axis  and  line  of 
apsides  holding  the  same  relation  to  each  other 
that  the  Martian  ones  do.  This  similarity  of 
aspect  is,  as  we  shall  see  later,  apparently  very 
curiously  reproduced  in  certain  peculiarities  of 
the  surfaces  of  the  two  planets.  But  with  Mars 
the  result  is  much  more  marked  on  account 
of  the  greater  eccentricity  of  his  orbit,  which 
is  .0931  as  against  the  Earth's  .0168. 

As  even  under  these  exaggerated  conditions 
his  two  polar  regions  show  much  alike,  modern 
theories  about  our  glacial  epochs  are  consider- 
ably shaken. 


SIZE  AND  SHAPE 

The  last  of  the  preliminary  points  to  be  taken 
up  is  the  form  of  the  planet.  Consideration  of 
it  makes  in  some  sort  a  bridge  from  the  planet's 
past  to  its  present.  For  its  deviation  from  a 
perfect  sphere  tells  us  something  of  its  history. 

Between  the  shapes  of  the  large  planets, 
Jupiter,  Saturn,  Uranus,  and  probably  Neptune, 
and  those  of  the  small  ones,  Mercury,  Venus, 
the  Earth,  and  Mars,  there  is  a  striking  dis- 
similarity, the  former  being  markedly  oblate 
spheroids,  the  latter  almost  perfect  spheres. 

Into  the  cause  of  this,  very  interesting  as  it 
is,  we  have  not  here  space  to  go.  The  effect, 
however,  is  so  noticeable  that  while  the  most 
casual  glance  at  the  disk  of  Jupiter  will  reveal 
its  ellipticity,  the  most  careful  scrutiny  would 
fail  to  show  Mars  other  than  perfectly  round. 

Nevertheless,  the  planet  is  slightly  flattened 
at  the  poles.  Measures  have  repeatedly  been 
made  to  determine  the  extent  of  this  flattening, 
with  surprisingly  discordant  results,  most  of  the 
values  being  much  too  large. 

Observations  at  Flagstaff  during  this  last  op- 
position have  not  only  shown  that  most  of  the 
values  were  too  large,  but  have  revealed  the 
cause  of  their  discrepancy.  There  turns  out  to 
be  a  factor  in  the  case,  hitherto  unsuspected, 
whose  presence  proves  to  be  precisely  such  as 
would  cause  the  observed  variations  in  measure- 
ments. It  not  only  accounts  for  the  fact  of 


26  MARS 

discrepancy,  but  for  the  further  fact  that  the 
discrepancies  should  usually  be  on  the  side  of 
an  increase  of  the  apparent  polar  flattening. 
This  factor  is  the  recognition  of  a  perceptible 
twilight  upon  the  planet,  not  only  of  enough 
account  to  be  visible,  but  to  have  been  actually 
measured,  quite  unconsciously,  by  Mr.  Douglass, 
and  disclosed  only  when  the  measures  came  to 
be  compared  with  each  other.  Of  this  I  shall 
speak  more  at  length  when  we  reach  the  sub- 
ject of  atmosphere.  Here  it  is  only  necessary 
to  say  that  the  presence  of  a  twilight  fringing 
the  surface  of  the  planet  would  have  the  effect 
of  increasing  the  apparent  size  of  the  equatorial 
diameter  at  all  times,  but  to  a  different  degree 
at  different  times,  and  almost  always  more  than 
it  would  the  polar  one.  In  consequence,  the 
polar  flattening,  which  is  the  ratio  borne  by  the 
difference  of  the  equatorial  and  polar  diameters 
to  the  equatorial  diameter,  would  be  seemingly 
increased. 

The  value  of  Mr.  Douglass'  measures  is  height- 
ened by  a  certain  happy  event  of  an  unprece- 
dented nature,  —  the  first  observed  disappear- 
ance of  the  polar  cap,  and  that  at  the  very 
time  the  most  important  measures  were  made. 
The  presence  of  the  polar  cap  enters  as  a  dis- 
turbing element  into  measures  of  the  planet's 
disk,  on  account  of  the  increased  irradiation  it 
causes  at  the  extremity  of  the  polar  diameter, 


SIZE  AND  SHAPE  27 

which  makes  the  polar  diameter  measure  more 
than  it  otherwise  would.  For  the  polar  cap  is 
the  most  brilliant  part  of  the  disk ;  and  for  the 
same  reason  that  any  bright  body  seems  larger 
than  a  dark  one  of  the  same  size,  it  dilates  the 
planet  unduly  in  that  direction.  The  resulting 
effect  is  further  complicated  by  the  fact  that 
the  polar  cap  is  eccentrically  situated  with  re- 
gard to  the  pole  of  rotation,  as  we  shall  see 
later ;  and  as  the  pole  is  tilted,  the  cap  is  some- 
times on  the  edge  of  the  disk  and  the  irradia- 
tion in  consequence  large,  and  sometimes  well 
on  the  disk  itself  where  its  irradiation  is  little 
or  nothing.  As  the  amount  of  its  magnifying 
effect  is  not  accurately  known,  there  enters  with 
it  an  unknown  error.  Now,  last  autumn  Nature 
herself  kindly  eliminated  this  source  of  error. 

The  measures  made  by  Mr.  Douglass  are  thus 
entitled  to  special  regard,  not  only  because  of 
their  number  (a  great  many  of  them  were 
taken),  but  chiefly  because  Nature  made  the 
disturbing  influence  of  the  polar  cap  nil.  When, 
in  addition,  the  twilight  arc  is  allowed  for,  the 
measures  show  a  most  satisfactory  accordance 
and  give  for  the  value  of  the  polar  flattening 
ifa  of  the  equatoml  diameter. 

Now,  it  is  interesting  that  this  value  should 
receive  corroborative  support  from  two  quite 
different  directions.  The  first  of  these  is  that 
sirr  is  just  about  the  flattening  which  would  re- 


28  MARS 

suit  from  the  most  probable  supposition  we  can 
make  as  to  the  past  history  of  the  planet.  To 
show  this  we  may  take  the  case  of  the  Earth. 
Investigations  along  several  different  lines  all 
result  in  showing  that  the  polar  flattening  of 
the  Earth  is  almost  exactly  such  as  would  re- 
sult in  a  fluid  body  whose  density  from  surface 
to  centre  increased  according  to  the  pressure 
and  temperature  of  our  Earth  in  the  past,  and 
which  rotated  with  its  present  angular  velocity. 
In  the  case  of  Mars,  Tisserand  has  shown  that 
the  polar  flattening  under  the  influence  of  his 
present  rotation  would,  if  the  increase  of  den- 
sity in  his  strata  were  similar  to  the  Earth's, 
be  2i2T  of  his  equatorial  diameter.  If,  on  the 
other  hand,  his  mass  were  homogeneous,  his 
polar  flattening  would  be  jfa.  Now,  in  a  fluid 
condition  a  body  could  not  remain  homogene- 
ous, owing  to  the  pressure  exerted  by  the  outer 
strata  upon  the  inner  ones,  unless  the  matter  of 
which  it  was  composed  were  rigorously  incom- 
pressible, which  is  certainly  not  the  case  with 
the  Earth,  and  with  quite  equal  certainty  not 
the  case  with  Mars.  On  the  other  hand,  the 
increase  of  density  from  surface  to  centre  is  un- 
doubtedly less  in  Mars  than  in  the  Earth,  since 
the  pressure  depends  upon  the  mass  and  the 
Earth's  mass  is  nearly  ten  times  that  of  Mars. 
Consequently,  from  this  cause,  the  polar  flatten- 
ing should  be  somewhere  between  yy^  and  a^y, 


SIZE  AND  SHAPE  29 

not  far  therefore  from  the  value  found  above, 

T9T7- 

The  second  bit  of  corroborative  testimony 
comes  from  the  behavior  of  the  satellites  of 
the  planet.  Unlike  a  sphere,  a  spheroid  acts 
unequally  upon  a  body  revolving  about  it  in 
an  ellipse  inclined  to  its  equator.  The  ring 
pulls  the  satellite  now  this  way,  now  that,  thus 
altering  its  nodes,  that  is,  the  points  where 
the  plane  of  its  orbit  crosses  the  planet's  equa- 
tor, and  also  its  apsides,  or  the  points  in 
which  the  satellite's  orbit  is  nearest  and  farthest 
from  the  planet.  The  effect  of  an  equatorial 
protuberance  tilted  thus  is  to  shift  these  points 
round  the  orbit,  the  line  of  nodes  retrograding, 
while  contrarily  the  line  of  apsides  advances. 
From  the  speed  with  which  these  revolutions 
take  place,  it  is  possible  to  calculate  the  size  of 
the  bulge.  Hermann  Struve  has  just  done  this 
for  the  lines  of  apsides  of  the  two  satellites  of 
Mars,  and  finds  for  the  value  for  the  consequent 
polar  flattening  of  the  planet  yj^  of  its  equa- 
torial diameter.  From  these  two  independent 
determinations  we  may  conclude  that  the  value 
found  at  Flagstaff  is  pretty  nearly  correct. 

We  find,  then,  that  Mars  is  a  little  flatter 
than  our  Earth,  though  not  noticeably  so,  the 
polar  flattening  amounting  to  about  22  miles. 

The  value,  yJu-,  for  his  polar  flattening,  hints 
that  at  some  past  time  Mars  was  in  a  fluid  — 


30  MARS 

that  is,  a  molten — condition,  just  as  the  Earth's 
polar  flattening  of  3-^3  similarly  shows  her  to 
have  been,  and  that  in  both  cases  the  flatten- 
ing was  then  impressed.  Now,  inasmuch  as  the 
tides,  lunar  and  solar  in  the  case  of  the  Earth, 
solar  practically  alone  in  the  case  of  Mars,  have 
been  slowing  up  the  planet's  rotation  ever  since 
this  refrigeration  happened,  but  as  their  respec- 
tive rates  of  rotation  still  agree  substantially 
with  what  a  fluid  condition  demands,  it  is  evi- 
dent that  in  the  case  of  neither  planet  could 
the  cooling  have  begun  so  very  long  ago,  but 
that  it  began  longer  ago  for  Mars  than  for  the 
Earth. 

In  so  far,  then,  we  trace  a  certain  similarity 
of  development  in  the  early  chaotic  stage  of 
evolution  of  the  two  planets,  a  stage  pre-natal 
to  their  career  as  worlds. 

From  these  basic  facts  of  size  and  shape  we 
will  now  go  on  to  more  latter-day  detail. 


n 

ATMOSPHERE 
I.    EVIDENCE   OF   IT 

To  all  forms  of  life  of  which  we  have  any 
conception,  two  things  in  nature  are  vital,  air 
and  water.  A  planet  must  possess  these  two 
requisites  to  be  able  to  support  any  life  at  all 
upon  its  surface.  For  there  is  no  creature,  no 
plant,  no  anything  endowed  with  the  possi- 
bility of  that  kind  of  change  we  call  life,  which 
is  not  in  some  measure  dependent  upon  both  of 
them.  How,  then,  is  Mars  off  for  air  ? 

Fortunately  for  an  answer  to  this  question, 
air,  in  the  post-chaotic  part  of  a  planet's  career, 
plays  as  vital  a  role  in  the  inorganic  processes 
of  nature  as  in  the  organic  ones.  By  the  post- 
chaotic  period  of  a  planet's  history  we  may  des- 
ignate that  time  in  its  evolutionary  existence 
which  follows  the  parting  with  its  own  inherent 
heat.  After  its  heat  has  gone  from  it,  atmos- 
phere becomes  essential,  not  only  to  any  form 
of  life  upon  its  surface,  but  to  the  production  of 
any  change  whatever  there.  Without  atmos- 
phere all  development,  even  the  development 


32  MARS 

of  decay,  must  come  to  a  stand-still,  when  once 
what  was  friable  had  crumbled  to  pieces  under 
the  alternate  roasting  and  refrigerating,  rela- 
tively speaking,  to  which  the  body's  surface 
would  be  exposed  as  it  turned  round  on  its  axis 
into  and  out  of  the  Sun's  rays.  Such  disinte- 
gration once  accomplished,  the  planet  would  roll 
thenceforth  a  mummy  world  through  space. 

An  instance  of  this  death  in  life  we  have  ex- 
emplified by  the  nearest  of  the  heavenly  bodies, 
our  own  Moon.  That  cataclysmic  changes  once 
occurred  there  is  still  legible  on  her  face,  while 
the  present  well-nigh  complete  immutability  of 
that  face  shows  that  next  to  nothing  happens 
there  now.  Except  for  the  possible  tumbling 
in  of  a  crater  wall,  such  as  seems  to  have  taken 
place  in  the  case  of  Linne  a  few  years  ago,  all 
is  now  deathly  still.  But  atmosphere  is  as  ab- 
sent as  change.  Whatever  it  may  have  had  in 
the  past,  there  is  at  present  no  perceptible  air 
upon  the  surface  of  the  Moon.  And  change 
pro  tanto  knows  it  no  more. 

With  Mars  it  is  otherwise.  Over  the  surface 
of  that  planet  changes  do  occur,  changes  upon  a 
scale  vast  enough  to  be  visible  from  the  Earth. 
To  appreciate  the  character  and  extent  of  these 
changes  we  will  begin  with  the  appearance  of 
the  planet  last  June.1  From  the  drawings  it 
will  be  seen  that  the  general  aspect  of  the 

1  Plates  V.,  VI.,  VII.     Uppermost  figure. 


ATMOSPHERE  33 

planet's  surface  at  that  time  was  tripartite. 
Upon  the  top  part  of  the  disk,  round  what  we 
know  to  be  the  planet's  pole,  appeared  to  be  a 
great  white  cap.  This  was  the  planet's  south 
polar  cap.  The  south  lay  at  the  top,  because 
all  astronomical  views  are,  for  optical  reasons, 
upside  down;  but,  inasmuch  as  we  never  see 
the  features  otherwise,  to  have  them  right  side 
up  is  not  vital  to  the  effect.  Below  the  white 
cap  lay  a  region  chiefly  bluish-green,  inter- 
spersed, however,  with  portions  more  or  less 
reddish-ochre.  Below  this,  again,  came  a  vast 
reddish-ochre  stretch. 

The  first  sign  of  change  occurred  in  the  polar 
cap.  It  proceeded  slowly  to  dwindle  in  size. 
Such  self-obliteration  it  has,  with  praiseworthy 
regularity,  been  seen  to  undergo  once  every 
two  years  since  it  was  first  seen  by  man.  For 
nearly  two  hundred  years  now,  it  has  been 
observed  to  wax  and  wane  with  clock-like  pre- 
cision, a  precision  timed  to  the  change  of  sea- 
son in  the  planet's  year.  During  the  spring, 
these  snow-fields,  as  analogy  at  once  guesses 
them  to  be,  and  as  beyond  doubt  they  really 
are,  stretch  in  the  southern  hemisphere,  the 
one  presented  to  us  at  this  last  opposition,  down 
to  latitude  sixty-five  south  and  even  further, 
covering  thus  more  than  the  whole  of  the 
planet's  frigid  zone.  As  summer  comes  on, 
they  dwindle  gradually  away,  till  by  early  au- 


34  MARS 

tumn  they  present  but  tiny  patches  a  few  hun- 
dred miles  across.  This  year,  for  the  first  time 
in  human  experience,  they  melted,  apparently, 
completely. 

The  history  of  the  cap's  vicissitudes  we  shall 
take  up  farther  on  in  connection  with  the  ques- 
tion of  water.  It  is  only  necessary  here  to  note 
that  changes  occurred  in  it. 

The  disappearance  of  the  polar  snows  is  by 
no  means  the  only  change  discernible  upon  the 
surface  of  the  planet.  Several  years  ago  Schia- 
parelli  noticed  differences  in  tint  at  successive 
oppositions  both  in  the  dark  areas  and  in  the 
bright  ones.  These,  he  suggested,  might  be 
due  to  seasons.  At  the  last  opposition,  that  of 
1894,  it  was  possible  at  Flagstaff,  owing  to  the 
length  of  time  the  planet  was  kept  under  ob- 
servation, to  watch  the  changes  occur;  thus 
conclusively  proving  them  to  be  changes  of  a 
seasonal  character. 

From  early  in  June,  which  corresponded  to 
the  Martian  last  of  April,  to  the  end  of  Novem- 
ber, which  corresponded  to  the  Martian  last  of 
August,  the  bluish-green  areas  underwent  a 
marked  transformation.  During  the  summer 
of  the  Martian  southern  hemisphere,  a  wave  of 
seasonal  change  swept  down  from  the  pole  over 
the  face  of  the  planet.  What  and  why  it  was 
we  will  examine  in  detail  when  we  take  up  the 
question  of  water.  Like  the  changes  in  the 


ATMOSPHERE  35 

polar  cap,  it  suffices  here  to  chronicle  the  fact 
that  it  took  place  ;  for  the  fact  of  its  occurrence 
constitutes  proof  positive  of  the  presence  of  an 
atmosphere. 

A  moment's  consideration  will  show  how  ab- 
solutely positive  this  proof  is.  It  is  the  inevi- 
table deduction  from  the  simplest  of  observed 
facts.  Its  cogency  gains  from  its  very  sim- 
plicity. For  it  is  independent  of  difficult  detail 
or  of  doubtful  interpretation.  It  is  not  con- 
cerned with  what  may  be  the  constitution  of 
the  polar  caps,  nor  with  the  character  of  the 
transformation  that  sweeps,  wave-like,  over  the 
rest  of  the  planet's  face.  It  merely  takes  note 
that  change  occurs,  ano^  that  note  is  final. 

Now,  since  this  was  originally  written,  certain 
observations  made  at  this  observatory  by  Mr. 
Douglass  have  resulted  apparently,  most  unex- 
pectedly, in  actually  revealing  this  atmosphere 
to  sight.  Although  the  existence  of  an  atmos- 
phere is  absolutely  established  by  the  above 
considerations,  it  is  interesting  to  have  ocular 
demonstration  of  it  to  boot ;  and  this  the  more, 
that  it  would  not  have  been  thought  possible  to 
detect  what,  so  to  speak,  disclosed  itself.  For 
the  discovery  was  quite  unconsciously  made, 
being  of  the  nature  of  a  by-product  to  the 
outcome  of  another  investigation.  So  syste- 
matically was  his  general  search  conducted  that 
when  the  results  came  to  be  worked  out  it 


36  MARS 

appeared  not  only  that  he  had  seen  an  atmos- 
phere, but  actually  measured  it,  although  he 
was  quite  unaware  of  doing  so  at  the  time. 
The  occasion  was  the  measuring  of  the  diame- 
ters of  the  planet,  polar  and  equatorial.  Micro- 
metric  measures  of  these  were  begun  as  early 
as  the  beginning  of  July,  and  kept  up  at  inter- 
vals till  the  latter  part  of  November.  But  the 
ones  that  proved  specially  tell-tale  were  those 
made  from  September  20th  to  November  22d, 
a  set  of  polar  and  a  set  of  equatorial  ones  hav- 
ing been  taken  throughout  that  interval  on 
twenty-six  nights. 

Now,  when  these  measures  came  to  be  worked 
out  by  me,  corrected  for  all  known  sources  of 
error  and  reduced  to  distance  unity,  a  curi- 
ous result  made  its  appearance.  As  they 
stood  arranged  in  their  table  chronologically, 
it  was  at  once  evident,  even  before  taking  the 
means,  that,  as  time  went  on,  something  had 
affected  the  equatorial  diameter  which  had 
not  affected  the  polar  one. 

The  values  for  the  polar  diameter  were  nearly 
the  same  from  first  to  last.  The  equatorial 
values,  on  the  other  hand,  showed,  apparently, 
a  systematic  increase  as  the  eye  followed  down 
the  column.  Something,  therefore,  had  been 
at  work  on  the  one,  which  had  not  been  at 
work  on  the  other.  Almost  as  instantaneously, 
it  was  evident  what  this  something  was,  to  wit, 


ATMOSPHERE  37 

a  visible  twilight  unconsciously  measure^  for  a 
part  of  the  planet's  surface.  Like  the  Down- 
easter  who  shingled  fifty  feet  on  to  the  fog, 
Mr.  Douglass  had  measured  several  miles  into 
the  Martian  air. 

A  word  or  two  will  explain  this.  The  planet 
came  to  opposition  on  October  20.  The  mid- 
measures  of  the  series,  therefore,  were  taken 
within  a  few  days  of  opposition,  just  before  and 
just  after  that  event.  The  subsequent  ones, 
on  the  other  hand,  were  made  at  a  gradually 
increasing  distance  from  this  position,  as  the 
planet  passed  toward  quadrature.  Now,  at  op- 
position, the  disk  of  the  planet  is  full,  like  the 
full  Moon ;  while,  as  it  passes  to  quadrature,  it 
loses  something  of  itself,  becoming  gibbous,  as 
the  Moon  does  two  or  three  days  after  the  full. 
This  loss  from  phase  chiefly  affects  the  equa- 
torial diameter,  the  polar  one  remaining  sub- 
stantially unchanged  by  it.  It  would  remain 
absolutely  unchanged  if  the  planet  moved  in 
the  plane  of  the  ecliptic.  It  does  not  so  move, 
but  the  quantity  resulting  from  lack  of  accord- 
ance is  so  small  that  for  the  present  explana- 
tion it  may  be  neglected.  Now,  this  question 
of  phase  was  the  only  point,  practically,  in  which 
the  equatorial  and  polar  diameters  differed  dur- 
ing the  interval  under  consideration.  This, 
then,  was  the  clew  to  the  discrepancy. 

It  was  not,  however,  the  loss  of  phase  that 

r\  A  o  o  O 


MARS 


was  in  question.  That  would  have  decreased 
the  values  of  the  equatorial  diameter  instead  of 
increasing  them,  and,  what  is  more  immediately 
to  the  point,  the  correction  for  it  had  already 
been  made.  This  correction  is  easily  ascer- 
tained, for  it  depends  chiefly  upon  the  position 
of  the  planet  in  its  orbit,  which  is  known  with 
great  accuracy.  The  resulting  values,  there- 
fore, had  nothing  to  do  with  the  phase  correc- 
tion as  such,  but  they  did,  nevertheless,  have 
to  do  with  the  phase  itself. 


Sun  Throughout 


Earfli 
3d  fostfion) 


ATMOSPHERE  39 

To  see  exactly  how  this  is  possible,  let  us 
consider  the  effect  an  illuminated  atmosphere 
would  have  upon  the  measurements  in  ques- 
tion. To  make  matters  more  obvious  we  will 
introduce  a  diagram.  The  inner  circle  repre- 
sents a  section  of  the  planet  in  the  plane  of  the 
ecliptic ;  the  arrows,  the  directions  in  the  same 
plane  of  the  Sun  and  Earth  from  the  centre  of 
the  planet,  in  the  different  positions  to  be  con- 
sidered ;  and  the  outer  circle,  an  atmosphere 
surrounding  the  planet,  at  the  limit  at  which 
it  is  dense  enough  to  reflect  light. 

At  opposition  the  Earth  lay  very  nearly  in 
the  same  line  from  the  planet  as  the  Sun.  This 
is  shown  by  the  left-hand  arrow.  The  illumi- 
nated semi-circumference  of  the  planet's  surface, 
at  that  time  also  the  semi-circumference  seen 
from  the  Earth,  was  gdbp,  and  gop  was  the 
equatorial  diameter ;  g'a'b'p'  and  g'op'  the  semi- 
circumference  and  equatorial  diameter,  upon 
the  supposition  of  an  atmospheric  envelope  en- 
circling the  surface.  As  the  Earth  and  Mars 
passed  along  their  orbits,  the  line  from  Mars 
to  the  Earth  shifted  into  its  second  position, 
the  Sun  remaining  as  before.  The  illuminated 
part  of  the  surface  of  Mars  continued,  there- 
fore, to  be  gabp  ;  but  the  portion  of  this  illumi- 
nated surface  visible  from  the  Earth  was  only 
dbp,  the  part  gd  being  invisible  from  the  Earth, 
and  the  part  ph  lying  in  shadow.  If,  however, 


40  MARS 

there  were  an  atmosphere  capable  of  reflecting 
light  up  to  a  height  represented  by  the  greater 
circle,  the  Sun's  rays  would  strike  the  upper 
visible  limit  of  this  atmosphere,  not  at  p'  but  at 
s,  sr  being  drawn  parallel  to  the  line  from  o  to 
the  Sun.  The  measured  equatorial  diameter, 
which  is,  of  course,  the  projection  of  the  arc 
d'b's  on  the  line  d'hf,  would  be  d'f  instead  of  de, 
which  it  would  be  were  there  no  atmosphere. 
It  thus  appears  that  owing  to  side-lengthening, 
as  we  may  perhaps  style  this  reverse  of  fore- 
shortening, the  fringe  of  atmosphere  increases 
in  apparent  width  with  increase  of  phase,  to  an 
apparent  increase  of  the  equatorial  diameter. 

If,  now,  we  take  a  third  position  for  the  Earth 
where  Mars  shows  a  yet  greater  phase,  the  third 
arrow,  we  find  that  in  this  case  the  resulting 
apparent  increase  in  the  equatorial  diameter  is 
mn,  and  we  notice  that  mn  is  greater  than  ef, 
just  as  ef  was  greater  than  ppf  or  cc'.  That  is, 
we  see  that  the  apparent  increase  in  the  size  of 
the  equatorial  diameter  varies  directly,  accord- 
ing to  some  law,  with  the  increase  in  phase,  or, 
as  it  is  technically  put,  is  a  function  of  the 
phase. 

This  increase,  being  an  increase  in  the  meas- 
ure itself,  would  in  due  course  come  in  for  its 
share  of  all  the  corrections  applied  to  the  diame- 
ter. In  consequence,  that  diameter,  instead  of 
coming  out  simply  the  full  equatorial  diameter, 


ATMOSPHERE  41 

would  come  out  too  big  in  proportion  to  the 
amount  added  by  the  twilight  arc. 

Pursuant,  therefore,  to  the  supposition  that 
such  was  the  cause  of  the  increase,  I  took  the 
means  of  the  polar  and  of  the  equatorial  diame- 
ters with  regard  to  the  time  from  opposition,  at 
which  the  measures  were  made,  to  find  myself 
confronted  by  a  series  of  values  counterparting 
what  we  have  just  seen  would  be  given  by  the 
presence  of  a  visible  twilight  arc.  The  result- 
ing values  are :  — 

Polar  Diameters : 

October  15  to  23  inc.  9".35 

October  12  and  24  to  30  inc.        9".35 
November  2  to  21  inc.  9".36 

Equatorial  Diameters : 

October  15  to  23  inc.  9".40 

October  12  and  24  to  30  inc.        9//.43 
November  2  to  21  inc.  9//.53 

The  measure  of  the  12th  of  October  and 
those  of  the  24th  to  30th  are  taken  together, 
because  equidistant  from  opposition  on  Octo- 
ber 20. 

The  agreement  of  this  table  with  that  de- 
ducible  by  theory  from  the  effect  of  an  atmos- 
phere is  striking.  But  the  agreement  is  even 
more  exact  than  appears.  For,  as  the  polar 
axis  was  not  in  the  same  line  as  the  axis  of 
phase,  the  twilight  arc  to  some  extent  affected 
the  polar  diameter  at  all  times,  but  specially 


42  MARS 

during  November.     This  becomes  evident,  nu- 
merically, on   applying   the  correction   for  an 
atmosphere,  which  gives  the  following  values : 
Polar  Diameters : 

October  15  to  23  inc.  9". 32 

October  12  and  24  to  30  inc.        9".31 
November  2  to  21  inc.  9".32 

Equatorial  Diameters : 

October  15  to  23  inc.  9".37 

October  12  and  24  to  30  inc.        9".36 
November  2  to  21  inc.  9".37 

The  middle  values  are  evidently  somewhat 
too  small,  since  they  affect  both  the  polar  and 
equatorial  diameters  alike.  Otherwise  the  varia- 
tion in  the  values  of  the  same  diameter  is  less 
than  the  probable  errors  of  observation.  Tak- 
ing the  mean  of  all  but  the  middle  ones,  we 
deduce  the  value  for  the  polar  flattening  given 
above,  jfa  of  the  equatorial  diameter. 

From  the  correction  for  the  effect  of  the  at- 
mosphere, we  find  the  amount  of  the  twilight 
arc  upon  the  planet  visible  from  the  Earth  to 
be  about  10°.  That  of  the  Earth,  as  seen  from 
the  Earth's  surface,  is  18° ;  but  it  is  to  be  no- 
ticed that  here  the  point  of  view  is  important. 
From  the  topmost  layer  of  our  air  of  sufficient 
density  to  be  capable  of  reflecting  light  we  are 
but  forty  miles  away ;  from  the  corresponding 
layer  of  the  Martian  air  we  are  forty  millions 
of  miles  off.  We  cannot,  therefore,  expect  to 


ATMOSPHERE  43 

detect  the  one  to  the  same  extent  that  we  can 
the  other.  The  value,  then,  for  the  Martian 
twilight  arc  of  10°  is  simply  a  minimal  value, 
not  an  absolute  one.  The  twilight  arc  cannot, 
from  the  observations,  be  less  than  this,  but  it 
may  be  much  more. 

The  large  number  of  measures  from  which 
the  above  means  were  deduced  not  only  ren- 
ders error  in  the  result  less  likely,  but  shows 
that  result  to  be  due  to  air  pure  and  simple. 
This  appears  from  the  fact  that  the  observed 
increase  is  systematic.  For  its  systematic  char- 
acter proves  it  due  to  something  largely  trans- 
parent. It  is  because  it  is  chiefly  not  seen  that 
it  is  seen  at  all.  At  first  sight  this  deduction 
seems  paradoxically  surprising.  But,  in  consid- 
ering the  problem,  we  shall  realize  that  it  must 
be  so. 

If  what  was  seen  were  opaque,  as,  for  ex- 
ample, a  mountain,  then  in  certain  positions  it 
would  indeed  be  seen  projecting  beyond  the 
terminator,  —  for  example,  if  it  were  at  s  in 
the  diagram  on  page  38 ;  if,  on  the  other  hand, 
it  were  in  the  position  r,  it  would,  instead  of 
apparently  increasing,  decrease  the  diameter. 
Now,  as  the  rotation  of  the  planet  would  bring 
it  eventually  into  all  possible  positions,  it  would 
be  as  likely  on  any  one  occasion  to  be  measured 
in  a  position  to  decrease  the  diameter  as  to 
increase  it.  From  but  a  few  measures,  there- 


44  MARS 

fore,  it  might  appear  that  there  was  an  in- 
crease in  the  calculated  diameter,  or  it  might 
seem  that  there  was  a  decrease  from  it,  and 
either  would  be  equally  likely  to  happen.  If, 
however,  many  measures  were  made,  and  just 
in  proportion  as  they  were  many,  those  decreas- 
ing the  diameter  would  offset  those  increasing 
it,  and  the  mean  of  all  would  show  no  trace  of 
either.  In  the  mean  the  minus  quantity  would 
wipe  out  the  plus.  Indeed,  owing  to  the  fact 
that  both  the  Sun  and  the  Earth  are  not  infi- 
nitely far  off  from  Mars,  and  in  consequence 
that  all  the  lines  to  them  are  not  strictly  par- 
allel to  one  another,  the  decreasing  effect  would 
actually  slightly  exceed  the  increasing  effect, 
but  this  would  be  too  small  to  be  perceptible. 

The  same  argument  that  applies  to  moun- 
tains applies  to  clouds,  or  to  any  opaque  sub- 
stance. Sporadic  increase  might  be  due  to 
them ;  but  for  the  increase  to  be  systematic, 
it  is  necessary  that  the  substance  seen  should 
also  be  seen  through.  It  must  be  in  part  trans- 
parent. The  measures,  therefore,  not  only  dis- 
close the  presence  of  an  atmosphere,  but  do  so 
directly. 

Having  thus  seen  first  with  the  brain  and 
then  with  the  eye,  and  both  in  the  simplest 
possible  manner,  that  a  Martian  atmosphere 
exists,  we  will  go  on  to  consider  what  it  may 
be  like. 


ATMOSPHERE  45 

The  first  and  most  conspicuous  of  its  char- 
acteristics is  cloudlessness.  A  cloud  is  an  event 
on  Mars,  a  rare  and  unusual  phenomenon,  which 
should  make  it  more  fittingly  appreciated  there 
than  Ruskin  lamented  was  the  case  on  Earth, 
for  it  is  almost  perpetually  fine  weather  on  our 
neighbor  in  space.  From  the  day's  beginning 
to  its  close,  and  from  one  end  of  the  year  to 
the  other,  nothing  appears  to  veil  the  greater 
part  of  the  planet's  surface. 

This  would  seem  to  be  even  more  completely 
the  case  than  has  hitherto  been  supposed.  We 
read  sometimes  in  astronomical  books  and  arti- 
cles picturesque  accounts  of  clouds  and  mists 
gathering  over  certain  regions  of  the  disk,  hid- 
ing the  coast-lines  and  continents  from  view,  and 
then,  some  hours  later,  clearing  off  again.  Very 
possibly  this  takes  place,  but  not  with  the  cer- 
tainty imputed  to  it.  It  is  also  doubtful  if 
certain  effects  of  longer  duration  are  really 
attributable  to  such  cause.  For  closer  study 
reveals  another  cause  at  work,  as  we  shall  see 
later,. and  the  better  our  own  air  the  more  the 
Martian  skies  seem  to  clear.  Certainly  no  in- 
stance of  the  blotting  out  of  detail  upon  the 
surface  of  Mars  has  been  seen  this  year  at 
Flagstaff.  Though  the  planet's  face  has  been 
scanned  there  almost  every  night,  from  the  last 
day  of  May  to  the  end  of  November,  not  a 
single  case  of  undoubted  obscuration  of  any 


46  MARS 

part  of  the  central  portions  of  the  planet,  from 
any  Martian  cause,  has  been  detected  by  any 
one  of  three  observers.  Certain  peculiar  bright- 
ish  patches  have  from  time  to  time  been  noted, 
but,  with  a  courtesy  uncommon  in  clouds,  they 
have  carefully  refrained  from  obscuring  in  the 
slightest  degree  any  feature  the  observer  might 
be  engaged  in  looking  at. 

The  only  certain  dimming  of  detail  upon  the 
Martian  disk  has  been  along  its  bright  semi- 
circular edge  or  edges,  as  the  case  may  be,  — 
what  is  technically  called  its  limb.  Fringing 
this  is  a  permanent  lune  of  light  that  swamps  all 
except  the  very  darkest  markings  in  its  glare. 
This  limb-light  has  commonly  been  taken  as 
evidence  of  sunrise  or  sunset  mists  on  Mars. 
But  observations  at  Flagstaff  during  last  June 
show  that  such  cannot  be  the  case.  In  June 
Mars  was  gibbous,  —  that  is,  he  showed  a  face 
like  the  Moon  between  the  quarter  and  the 
full,  —  and  along  his  limb,  then  upon  his  own 
western  side,  lay  the  bright  limb-light,  stretch- 
ing inward  about  thirty  degrees.  Since  the  face 
turned  toward  us  was  only  in  part  illumined  by 
the  Sun,  the  centre  of  it  did  not  stand  at  noon, 
but  some  hours  later,  and  the  middle  of  the 
limb  consequently  not  at  sunrise,  but  at  about 
nine  o'clock  of  a  Martian  morning.  As  the 
limb-light  extended  in  from  this  thirty  degrees, 
or  two  hours  in  time,  the  mist,  if  mist  it  was, 


ATMOSPHERE  47 

must  have  lasted  till  eleven  o'clock  in  the  day. 
Furthermore,  it  must  have  been  mist  of  a  sin- 
gularly mathematical  turn  of  mind,  for  it 
stretched  from  one  pole  to  the  other,  quite 
oblivious  of  the  fact  that  every  hour  from  sun- 
rise to  sunset  lay  represented  along  the  limb, 
including  high  noon.  What  is  more,  as  the  disk 
passed,  in  course  of  time,  from  the  gibbous  form 
to  the  full,  and  then  to  the  gibbous  form  on  the 
other  side,  the  limb-light  obligingly  clung  to 
the  limb,  regardless  of  everything  except  its 
geometric  curve.  But  as  it  did  so,  the  eleven 
o'clock  meridian  swung  across  it  from  one  side 
of  the  disk  to  the  other.  As  it  passed  the 
centre  the  regions  there  showed  perfectly  clear ; 
not  a  trace  of  obscuration  visible  as  it  lay  be- 
neath the  observer's  eye. 

From  the  first  observation  it  is  evident  that 
Martian  sunrise  and  sunset  had  nothing  to  do 
with  the  phenomenon,  since  it  was  not  either 
Martian  sunrise  or  sunset  at  the  spot  where  it 
was  seen ;  and,  from  both  observations  taken 
together,  it  is  evident  that  the  phenomenon  did 
have  to  do  with  the  position  of  the  observer. 
For  nothing  on  Mars  had  changed  in  the  mean 
time;  but  only  the  point  of  view  of  the  observer 
on  Earth.  It  is  clear,  therefore,  that  it  was  not 
a  case  of  Martian  diurnal  meteorological  change, 
but  a  case  of  foreshortening  of  some  sort. 

To  what,  then,  was  the  limb-light  due  ?    At 


48  MARS 

first  sight,  it  would  seem  as  if  the  Moon  might 
help  us ;  for  the  Moon's  rim  is  similarly  ringed 
by  a  lune  of  light.  In  her  case  the  effect  has 
been  attributed  to  mountain  slopes  holding  the 
Sun's  light  at  angles  beyond  the  possibility  of 
plains.  But  Mars  has  few  mountains  worthy 
the  name.  His  terminator  —  that  is,  the  part 
of  the  disk  which  is  just  passing  in  or  out  of 
sunlight,  and  discloses  mountains  by  the  way  in 
which  they  catch  the  coming  light  before  the 
plains  at  their  feet  are  illuminated  —  shows 
irregularities  quite  inferior  to  the  lunar  ones, 
proving  that  his  elevations  and  depressions  are 
relatively  insignificant. 

Not  due,  then,  to  either  mountains  or  mist, 
there  is  something  we  know  that  would  produce 
the  effect  we  see,  —  dust  or  water  particles  in 
the  Martian  air ;  that  is,  just  as  the  Earth's 
atmosphere  is  somewhat  of  a  veil,  so  is  the 
Martian  one,  and  this  veiling  effect,  though 
practically  imperceptible  in  the  centre  of  the 
disk,  becomes  noticeable  as  we  pass  from  the 
centre  to  the  edge,  owing  to  the  greater  thick- 
ness of  the  stratum  through  which  we  look. 
At  thirty  degrees  from  the  edge,  our  line  of 
sight  pierces  twice  as  much  of  it  as  when  we 
look  plumb  down  upon  the  centre  of  the  disk, 
and  more  yet  as  we  approach  the  edge  itself ; 
in  consequence,  what  would  be  diaphanous  at 
the  centre  might  well  seem  opaque  toward  the 


ATMOSPHERE  49 

limb.  The  effect  we  are  familiar  with  on  Earth 
in  the  haze  that  always  borders  the  horizon,  — 
a  haze  most  noticeable  in  places  where  there  is 
dust,  or  ice,  or  water  in  the  air.  Here,  then, 
we  have  a  hint  of  the  state  of  things  on  Mars. 
Ice  particles  both  are  probable  and  would  give 
the  brilliancy  required. 

This  first  hint  receives  independent  support 
from  another  Martian  phenomenon.  Contrary 
to  what  the  distance  of  the  planet  from  the 
Sun  and  the  thinness  of  its  atmospheric  en- 
velope would  lead  us  to  expect,  the  climate  of 
Mars  appears  to  be  astonishingly  mild.  Whereas 
calculation  from  distance  and  atmospheric  den- 
sity would  put  its  average  temperature  below 
freezing,  thus  relegating  it  to  perpetual  ice,  the 
planet's  surface  features  imply  that  the  tem- 
perature is  relatively  high.  Observation  gives 
every  evidence  that  the  mean  temperature 
must  actually  be  above  that  of  the  Earth ;  for 
not  only  is  there  practically  no  sign  of  snow  or 
ice  outside  the  frigid  zone  at  any  time,  but  the 
polar  snow-caps  melt  to  a  minimum  quite  be- 
yond that  of  our  own,  affording  rare  chance 
for  quixotic  polar  expeditions.  Such  pleasing 
amelioration  of  the  climate  must  be  accounted 
for,  and  aqueous  vapor  seems  the  most  likely 
thing  to  do  it ;  for  aqueous  vapor  is  quite  spe- 
cific as  a  planetary  comforter,  being  the  very 
best  of  blankets.  It  acts,  indeed,  like  the  glass 


50  MARS 

of  a  conservatory,  letting  the  light-rays  in  and 
opposing  the  passage  of  the  heat-rays  out. 

The  state  of  things  thus  disclosed  by  observa- 
tion, the  cloudlessness  and  the  rim  of  limb-light, 
turns  out  to  agree  in  a  most  happy  manner 
with  what  probability  would  lead  us  to  expect ; 
for  the  most  natural  supposition  to  make  a 
priori  about  the  Martian  atmosphere  is  the  fol- 
lowing :  When  each  planet  was  produced  by 
fission  from  the  parent  nebula,  we  may  suppose 
that  it  took  with  it  as  its  birthright  its  propor- 
tion of  chemical  constituents ;  that  is,  that  its 
amount  of  oxygen,  nitrogen  and  so  forth  was 
proportional  to  its  mass.  Doubtless  its  place  in 
the  primal  nebula  would  to  a  certain  extent 
modify  the  ratio,  just  as  the  size  of  the  planet 
would  to  a  certain  extent  modify  the  relative 
amount  of  these  elements  that  would  thereupon 
enter  into  combination.  Supposing,  however, 
that  the  ratio  of  the  free  gases  to  the  other 
elements  remained  substantially  the  same,  we 
should  have  in  the  case  of  any  two  planets  the 
same  relative  quantity  of  atmosphere.  But  the 
size  of  the  planet  would  entirely  alter  the  dis- 
tribution of  this  air. 

Three  causes  would  all  combine  to  rob  the 
smaller  planet  of  efficient  covering,  on  the  gen- 
eral principle  that  he  that  hath  little  shall  have 
less. 

In  the  first  place,  the  smaller  the  planet  the 


ATMOSPHERE  51 

greater  would  be  its  volume  in  proportion  to 
its  mass,  because  the  materials  of  which  it  was 
composed,  being  subjected  to  less  pressure 
owing  to  a  lesser  pull,  would  not  be  crowded 
so  closely  together.  This  is  one  reason  why 
Mars  should  have  a  thinner  atmosphere  than 
our  Earth. 

Secondly,  of  two  similar  bodies,  spheres  or 
others,  the  smaller  has  the  greater  surface  for 
its  volume,  since  the  one  quantity  is  of  two 
dimensions  only,  the  other  of  three.  An  onion 
will  give  us  a  good  instance  of  this.  By  strip- 
ping off  layer  after  layer  we  reach  eventually 
a  last  layer  which  is  all  surface,  inclosing  no- 
thing. We  may,  if  we  please,  observe  something 
analogous  in  men,  among  whom  the  most  super- 
ficial contain  the  least.  In  consequence  of  this 
principle,  the  atmosphere  of  the  smaller  body 
finds  itself  obliged  to  cover  relatively  more  sur- 
face, which  still  further  thins  it  out. 

Lastly,  gravity  being  less  on  the  surface  of 
the  smaller  body,  the  atmosphere  is  less  com- 
pressed, and,  being  a  gas,  seizes  that  opportunity 
to  spread  out  to  a  greater  height,  which  renders 
it  still  less  dense  at  the  planet's  surface. 

Thus,  for  three  reasons,  Mars  should  have  a 
thinner  air  at  his  surface  than  is  found  on  the 
surface  of  the  Earth. 

Calculating  the  effect  of  the  above  causes 
numerically  we  find  that  on  this  a  priori  sup- 


52  MARS 

position  Mars  would  have  at  his  surface  an  at- 
mosphere of  about  fourteen  hundredths,  or  one 
seventh,  of  the  density  of  our  terrestrial  one. 

Observation  supports  this  general  supposi- 
tion ;  for  the  cloudless  character  of  the  Martian 
skies  is  precisely  what  we  should  look  for  in  a 
rare  air.  Clouds  are  congeries  of  globules  of 
water  or  particles  of  ice  buoyed  up  by  the  air 
about  them.  The  smaller  these  are,  the  more 
easily  are  they  buoyed  up,  because  gravity, 
which  tends  to  pull  them  down,  acts  upon  their 
mass,  while  the  resistance  they  offer  varies  as 
the  surface  they  present  to  the  air,  and  this  is 
relatively  greater  in  the  smaller  particles.  The 
result  is  that  the  smaller  particles  can  float  in 
thinner  air.  We  see  the  principle  exemplified 
in  our  terrestrial  clouds  ;  the  low  nimbus  being 
formed  of  comparatively  large  globules,  while 
the  high  cirrus  is  made  up  of  very  minute  par- 
ticles. If  we  go  yet  higher,  we  reach  a  region 
incapable  of  supporting  clouds  of  any  kind,  so 
rarefied  is  its  air.  This  occurs  about  five  miles 
above  the  Earth's  surface ;  and  yet  even  at  this 
height  the  density  of  our  air  is  greater  than  is 
the  probable  density  of  the  air  at  the  surface  of 
Mars.  "We  see,  therefore,  that  the  Martian  at- 
mosphere should  from  its  rarity  prove  cloudless, 
just  as  we  observe  it  to  be. 

So  far  in  this  our  investigation  of  the  Martian 
atmosphere  we  have  been  indebted  solely  to  the 


ATMOSPHERE  53 

principles  of  mathematics  and  molar  physics  for 
help,  and  these  have  told  us  something  about 
the  probable  quantity  of  that  atmosphere, 
though  silent  as  to  its  possible  quality.  On 
this  latter  point,  however,  molecular  physics 
turns  out  to  have  something  to  say;  for  an 
Irish  gentleman,  Dr.  G.  Johnstone  Stoney,  has 
recently  made  an  ingenious  deduction  from  the 
kinetic  theory  of  gases  bearing  upon  the  atmos- 
pheric envelope  which  any  planet  can  retain. 
His  deduction  is  as  acute  as  it  appears  from  ob- 
servation to  be  in  keeping  with  the  facts.  It 
is  this :  — 

The  molecular  theory  of  gases  supposes  them 
to  be  made  up  of  myriads  of  molecules  in  inces- 
sant motion.  What  a  molecule  may  be  nobody 
knows ;  some  scientists  supposing  it  to  be  a 
vortex  ring  in  miniature,  —  something  like  the 
swirl  made  by  a  teaspoon  drawn  through  a  cup 
of  tea.  But,  whatever  it  be,  the  idea  of  it 
accounts  very  creditably  for  the  facts.  The 
motion  of  the  molecules  is  almost  inconceivably 
swift  as  they  dart  hither  and  thither  through- 
out the  space  occupied  by  the  gas,  and  their 
speed  differs  for  different  gases.  From  the  ob- 
served relations  of  the  volumes  and  weights  of 
gases  to  the  pressures  to  which  they  are  sub- 
jected is  deduced  the  fact  of  this  speed  and 
its  amount.  It  appears  that  the  molecules  of 
oxygen  travel,  on  the  average,  at  the  rate  of 


54  MARS 

fifteen  miles  a  minute ;  and  those  of  hydrogen, 
which  are  the  fastest  known,  at  the  enormous 
speed  of  more  than  a  mile  a  second.  But  this 
average  velocity  may,  for  any  particular  mole- 
cule, be  increased  by  collisions  with  its  neigh- 
bors. The  maximum  speed  it  may  thus  attain 
Clerk-Maxwell  deduced  from  the  doctrine  of 
chances  to  be  sevenfold  the  average.  What 
may  thus  happen  to  one,  must  eventually  hap- 
pen to  all.  Sooner  or  later,  on  the  doctrine  of 
chances,  each  molecule  of  the  gas  is  bound  to 
attain  this  maximum  velocity  of  its  kind.  When 
it  is  attained,  the  molecule  of  oxygen  travels  at 
the  rate  of  one  and  eight  tenths  miles  a  second, 
the  molecule  of  water  vapor  at  the  rate  of  two 
and  one  half  miles  a  second,  and  the  molecule 
of  hydrogen  at  over  seven  miles  a  second,  or 
four  hundred  and  fifty  times  as  fast  as  our  fast- 
est express  train. 

Now,  if  a  body,  whether  it  be  a  molecule 
or  a  cannon-ball,  be  projected  away  from  the 
Earth's  surface,  the  Earth  will  at  once  try  to 
pull  it  down  again :  this  instinctive  holding 
on  of  Mother  Earth  to  what  she  has  we  call 
gravity.  In  the  cases  with  which  we  are  per- 
sonally familiar,  her  endeavor  is  eminently  suc- 
cessful, what  goes  up  coming  down  again.  But 
even  the  Earth  is  not  omnipotent.  As  the 
velocity  with  which  the  body  is  projected  in- 
creases, longer  and  longer  time  is  needed  for 


ATMOSPHERE  55 

the  Earth  to  overcome  it  and  compel  the  body's 
return.  Finally  there  would  be  reached  a  speed 
which  the  Earth  would  just  be  able  to  overcome 
if  she  took  an  infinite  time  about  it.  In  that 
case  the  body  would  continue  to  travel  away 
from  her,  at  a  constantly  diminishing  rate,  but 
still  at  some  rate,  on  and  on  into  the  depths  of 
space,  if  there  were  no  other  bodies  in  the  uni- 
verse but  the  Earth  and  the  molecule,  till  it 
attained  infinity,  at  which  point  the  truant 
would  stop,  and  then  reluctantly  return.  This 
velocity  we  may  call  the  critical  velocity.  It 
is  also  known  as  the  parabolic  velocity,  because 
it  is  at  any  point  the  velocity  of  a  body  moy- 
ing  in  a  parabola  about  the  Earth,  under  the 
Earth's  attraction ;  the  parabola  being  the  curve 
of  a  fall  from  infinity.  The  critical  velocity  is 
the  parabolic  velocity,  inasmuch  as  gravity  is 
able  to  destroy  on  the  way  up  just  the  speed  it 
is  able  to  impart  on  the  way  down.  But,  now, 
if  the  body's  departure  were  even  hastier  than 
this,  the  Earth  would  never  be  able  wholly  to 
annihilate  its  speed,  and  the  body  would  travel 
out  and  out  forever.  If  its  speed  at  starting 
were  less  than  twenty-seven  miles  a  second,  it 
would  become  thenceforth  a  satellite  of  the 
Sun  ;  if  its  speed  were  yet  greater,  it  would 
become  an  independent  rover  through  space, 
paying  brief  visits  only  to  star  after  star.  In 
any  case  the  Earth  would  know  the  vagabond 
no  more. 


56  MARS 

As  gravity  depends  upon  mass,  the  larger  the 
attracting  planet  the  greater  is  its  critical  ve- 
locity, the  velocity  it  can  just  control ;  and, 
reversely,  the  smaller  the  planet  the  less  its 
restraining  power.  With  the  Earth  the  critical 
velocity  is  six  and  nine  tenths  miles  a  second. 
If  any  of  us,  therefore,  could  manage  to  acquire 
a  speed  greater  than  this,  socially  or  otherwise, 
we  could  bid  defiance  to  the  whole  Earth,  and 
begin  to  voyage  on  our  own  account  through 
space.1 

This  speed  is  actually  attained,  as  we  have 
seen,  by  the  molecules  of  hydrogen.  If,  there- 
fore, a  molecule  of  free  hydrogen  were  present 
at  the  surface  of  the  Earth,  and  met  with  no 
other  gas  attractive  enough  to  tie  it  down  by 
uniting  with  it,  the  rover  would,  in  course  of 
time,  attain  a  speed  sufficient  to  allow  it  to  bid 
good-by  to  Earth,  and  start  on  interspacial 
travels  of  its  own.  That  it  should  reach  its 
maximum  speed  is  all  that  is  essential  to  lib- 
erty, the  direction  of  its  motion  being  immate- 
rial. To  molecule  after  molecule  would  come 
this  happy  dispatch,  till  the  Earth  stood  de- 
prived of  every  atom  of  free  hydrogen. 

Now,  it  is  a  highly  significant  fact  that  there 
is  no  free  hydrogen  found  in  the  Earth's  atmos- 
phere. There  is  plenty  of  it  in  the  captivit}' 
of  chemical  combination,  but  none  in  the  free 

1  See  Appendix. 


ATMOSPHERE  57 

state.  This  coincidence  of  lack  of  hydrogen 
with  lack  of  liberty  takes  on  yet  more  signifi- 
cance from  the  further  fact  that  the  same  is  not 
true  of  oxygen,  water  vapor,  or  indeed  of  any 
of  the  other  gases  we  know.  With  them,  free- 
dom is  not  synonymous  with  absence.  The 
Earth's  atmosphere  contains  plenty  of  free  oxy- 
gen, nitrogen,  and  the  like.  But,  as  we  have 
just  seen,1  the  maximum  speed  of  all  these  gases 
falls  short  of  the  possibility  of  escape.  This 
accounts  for  their  presence.  They  have  stayed 
with  us  solely  because  they  must. 

The  appearance  of  the  other  heavenly  bodies 
seems  to  confirm  this  conclusion.  The  Moon, 
for  example,  possesses  no  atmosphere,  and  cal- 
culation shows  that  the  velocity  it  can  control 
falls  short  of  the  maximum  of  any  of  our  atmos- 
pheric gases,  that  velocity  being  but  one  and 
one  half  miles  a  second.  All  were,  therefore, 
at  liberty  to  leave  it,  and  all  have  promptly 
done  so.  On  the  other  hand,  the  giant  planets 
give  evidence  of  very  dense  atmospheres.  They 
have  kept  all  they  ever  had. 

But  the  most  striking  confirmation  of  the 
theory  comes  from  the  cusps  of  Venus  and 
Mercury;  for  an  atmosphere  would  prolong, 
by  its  refraction,  the  cusps  of  a  crescent  beyond 
their  true  limits.  Length  of  cusp  becomes,  con- 
sequently, a  criterion  of  the  presence  of  an  at- 

1  See  Appendix. 


58  MAES 

mosphere.  Now,  in  the  appearance  of  their 
cusps  there  is  a  notable  difference  between 
Venus  and  Mercury.  The  cusps  of  Venus  ex- 
tend beyond  the  semi-circle ;  Mercury's  do  not. 
We  see,  therefore,  that  Mercury  has  apparently 
little  or  no  atmospheric  envelope,  and  we  find 
that  his  critical  velocity  is  only  2.2  miles  per 
second,  —  below  that  of  water  vapor,  and  peril- 
ously near  that  of  nitrogen  and  oxygen. 

Turning  to  the  case  of  Mars,  we  find  with 
him  the  critical  velocity  to  be  three  and  one 
tenths  miles  a  second.  Now,  curiously  enough, 
this  is,  like  the  Earth's,  below  the  maximum 
for  the  molecules  of  hydrogen,  but  also,  like 
the  Earth's,  above  that  of  any  other  gas ;  from 
which  we  have  reason  to  suppose  that,  except 
for  possible  chemical  combinations,  his  atmos- 
phere is  in  quality  not  very  unlike  our  own. 

Having  seen  what  the  atmosphere  of  Mars  is 
probably  like,  we  may  draw  certain  interesting 
inferences  from  it  as  to  its  capabilities  for  mak- 
ing life  comfortable.  The  first  consequence  of 
it  is  that  Mars  is  blissfully  destitute  of  weather. 
Unlike  New  England,  which  has  more  than  it 
can  accommodate,  Mars  has  none  of  the  article. 
What  takes  its  place  there,  as  the  staple  topic 
of  conversation  for  empty-headed  folk,  remains 
one  of  the  Martian  mysteries  yet  to  be  solved. 
What  takes  its  place  in  fact  is  a  perpetual 
serenity  such  as  we  can  scarcely  conceive  of. 


ATMOSPHERE  59 

Although  over  what  we  shall  later  see  to  be 
the  great  continental  deserts  the  air  must  at 
midday  be  highly  rarefied,  and  cause  vacuums 
into  which  the  surrounding  air  must  rush,  the 
actual  difference  of  gradient,  owing  to  the  initial 
thinness  of  the  air,  must  be  very  slight.  "With 
a  normal  barometer  of  four  and  a  half  inches, 
a  very  great  relative  fall  is  a  very  slight  actual 
one.  In  consequence,  storms  would  be  such 
mild-mannered  things  that,  for  objectionable 
purposes,  they  might  as  well  not  be.  In  the 
first  place,  there  can  be  but  little  rain,  or  hail, 
or  snow,  for  the  particles  would  be  likely  to 
be  deposited  before  they  gained  the  dignity  of 
such  separate  existence.  Dew  or  frost  would 
be  the  common  precipitation  on  Mars.  The 
polar  snow-cap  or  ice-cap,  therefore,  is  doubt- 
less formed,  not  by  the  falling  of  snow,  but  by 
successive  depositions  of  dew.  Secondly,  there 
would  be  about  the  Martian  storms  no  very 
palpable  wind.  Though  the  gale  might  blow 
at  fairly  respectable  rates,  so  flimsy  is  the  sub- 
stance moved  that  it  might  buffet  a  man  un- 
mercifully without  reproach. 

Another  interesting  result  of  the  rarity  of 
the  air  would  be  its  effect  upon  the  boiling- 
point  of  water.  Reynault's  experiments  have 
shown  that,  in  air  at  a  density  ^  of  our  own, 
water  would  boil  at  about  127°  Fahrenheit. 
This,  then,  would  be  the  temperature  at  which 


60  MARS 

water  would  be  converted  into  steam  on  Mars. 
So  low  a  boiling-point  would  raise  tbe  relative 
amount  of  aqueous  vapor  held  in  suspension  by 
the  air  at  any  temperature.  At  about  127°  the 
air  would  be  saturated,  and  even  at  lower  tem- 
peratures much  more  of  it  would  evaporate  and 
load  the  surrounding  air  than  happens  at  similar 
temperatures  on  Earth.  Thus  at  the  heels  of 
similarity  treads  contrast. 

We  may  now  go  on  to  some  phenomena  of 
the  Martian  atmosphere  of  a  more  specific  char- 
acter. 

II.     CLOUDS 

Although  no  case  of  obscuration  has  been 
seen  at  Flagstaff  this  summer,  certain  parts  of 
the  planet's  disk  have  appeared  unaccountably 
bright  at  certain  times.  That  these  are  not 
storm-clouds,  like  those  which,  by  a  wave-like 
process  of  generation,  travel  across  the  Ameri- 
can continent,  for  example,  is  shown  by  the 
fact  that  they  do  not  travel,  but  are  local  fix- 
tures. Commonly,  the  same  places  appear 
bright  continuously  day  after  day  and  recur- 
rently year  after  year,  different  astronomers  at 
successive  oppositions  having  so  observed  them. 
To  this  category  belong  the  regions  known  as 
Elysium,  Ophir,  Memnonia,  Eridania,  and 
Tempe,  which  at  certain  seasons  of  the  Martian 
year  are  phenomenally  brilliant.  They  stay  so 
for  some  time,  and  then  the  brightness  fades  out 


CLOUDS  61 

to  appear  again  at  the  next  opposition.  Still 
smaller  bright  spots,  apparently  more  fugitive, 
have  been  seen  this  year  by  Professor  W.  H. 
Pickering,  notably  just  north  of  the  Mare  Si- 
renum.  None  of  the  phenomena  look  distinc- 
tively like  cloud.  There  are,  however,  pheno- 
mena that  do. 

Toward  the  end  of  August  there  were  seen 
several  times,  first  by  Professor  Pickering  and 
then  by  me,  strange  flocculent  collections  of 
white  patches,  about  fifteen  degrees  from  the 
pole,  in  the  place  where  the  snow-cap  had  been, 
the  cap  itself  having  retreated  farther  south. 
In  look  they  were  unlike  the  snow-cap;  and 
also  unlike  the  land.  But  they  did  have  very 
much  the  look  of  clouds.  Possibly  they  were 
clouds,  formed  from  the  vapor  left  in  the  air  by 
the  melting  of  the  cap.  It  was  then  but  a  few 
days  to  the  summer  solstice. 

But  the  most  marked  instance  of  variability 
was  detected  in  September  last  by  Mr.  Doug- 
lass in  the  western  part  of  Elysium.  On  Sep- 
tember 22  and  23  he  found  this  blissfully 
bright  region,  as  usual,  equally  bright  through- 
out. But  on  September  24  he  noticed  that 
the  western  half  of  it  had  suddenly  increased  in 
brightness,  and  far  outshone  the  eastern  half, 
being  almost  as  brilliant  as  the  polar  cap. 
When  he  looked  at  it  again  the  next  night, 
September  25,  the  effect  of  the  night  before 


62  MARS 

had  vanished,  the  western  half  being  now  ac- 
tually the  darker  of  the  two.  So  fugitive  an 
effect  suggests  cloud,  forming  presumably  over 
high  ground,  and  subsequently  dissipating ;  it 
also  suggests  a  deposition  of  frost,  melting  on 
the  next  day.  It  is  specially  noteworthy  that 
the  canals  inclosing  the  region,  the  Galaxias,  the 
Boreas,  and  the  Eunostos,  were  not  in  any  way 
obscured  by  the  bright  apparition.  On  the  con- 
trary, Mr.  Douglass  found  them  perceptibly 
darker  than  they  had  been,  an  effect  attributable 
perhaps  to  contrast. 

Although  not  storm-clouds,  it  is  possible  that 
these  appearances  may  have  been  due  to  thin 
cloud,  capping  high  land.  There  are  objections 
to  this  view,  but  as  there  are  graver  ones 
to  any  other  it  may  stand  provisionally,  the 
more  so  that  there  are  appearances  not  easily 
reconcilable  with  other  cause.  For  example,  a 
most  singular  phenomenon  was  seen  by  Mr. 
Douglass  on  November  25,  a  bright  detached 
projection,  for  which,  from  measurement,  he 
deduced  a  height  of  thirty  miles.  This  would 
seem  to  have  been  cloud,  for  the  details  of  its 
changes  in  appearance  seem  quite  incompatible 
with  a  mountainous  character.  With  regard  to 
its  enormous  height,  it  is  not  to  be  forgotten 
that  a  few  years  ago  on  the  Earth  phenomenal 
dust-clouds  were  observed  as  high  as  one  hun- 
dred miles. 


CLOUDS  63 

"We  now  come  to  a  highly  interesting  class 
of  observations  bearing  upon  the  question  of 
clouds,  —  Mr.  Douglass's  terminator  observa- 
tions. During  the  last  opposition,  seven  hundred 
and  thirty-six  irregularities  upon  the  terminator 
of  the  planet  were  detected  at  Flagstaff.  They 
were  seen  by  one  or  more  of  three  observers, 
but  chiefly  by  Mr.  Douglass,  who  made  a  syste- 
matic scrutiny  of  the  terminator  for  almost 
every  degree  of  Martian  longitude.  Their  full 
presentation  would  be  both  too  tabular  and  too 
technical  for  this  book.  The  paper  embodying 
them  will  be  found  among  the  published  annals 
of  this  observatory.  I  shall  here  give  only  cer- 
tain deductions  from  it. 

Of  the  736  irregularities  observed,  694  were 
not  only  recorded  but  measured.  Of  these  403 
were  depressions.  It  is  singular,  in  view  of 
their  easy  visibility,  that  they  never  should 
have  been  noticed  before.  Schroeter,  indeed, 
saw  three  appearances  of  the  sort,  —  on  Septem- 
ber 21, 1798,  November  12, 1800,  and  December 
18, 1802,  —  but  all  on  the  limb,  not  the  termina- 
tor, which  shows  them  not  to  have  been  of  those 
here  meant.  Nevertheless  they  are  not  difficult 
to  see,  and  anything  but  rare.  When  the  phase 
is  large  enough,  several  may  be  seen  every  night. 

The  projections  number  291.  As  their  num- 
ber shows,  they  are  less  common  than  the  de- 
pressions, but  they  are  even  less  of  a  feature  of 


64  MAES 

the  surface  than  their  number  would  indicate, 
for  the  depressions  extend  as  a  rule  much  fur- 
ther both  in  latitude  and  longitude. 

Usually  the  depressions  look  like  parings  from 
the  planet's  rind,  and  almost  always  appear  upon 
that  part  of  the  terminator  where  the  dark  re- 
gions are  passing  out  of  sight ;  commonly  there- 
fore, in  the  case  of  the  southern  hemisphere, 
they  are  met  with  between  latitudes  30°  to  60° 
south.  Not  so  common  is  it  for  them  to  occur 
over  a  part  of  the  planet  which  is  bright. 
Furthermore,  they  appear  to  occur  more  or  less 
continuously.  This  would  not  be  the  case  were 
they  real  depressions. 

As  this  may  not  at  once  be  evident  to  the 
reader,  and  yet  is  easily  made  evident,  we  will 
consider  the  diagram  on  page  38.  It  will  there 
be  seen  that  an  elevation  like  s  or  r  —  and  the 
same  reasoning  applies  mutatis  mutandis  to  a 
depression  —  appears  projected  a  relatively  long 
way  without  or  within  the  terminator,  as  com- 
pared with  its  actual  length,  owing  to  the  angles 
under  which  it  is  respectively  illuminated  by 
the  Sun  and  seen  from  the  Earth.  The  rela- 
tion between  its  height  and  its  distance  from  the 
edge  is  that  between  the  height  of  a  hill  and 
the  shadow  it  casts  at  sunrise  or  sunset.  What, 
therefore,  is  not  high  enough  to  be  seen  in  pro- 
file on  the  limb,  becomes  vicariously  visible  on 
the  terminator.  But  a  hill  could  not  continue 


CLOUDS  65 

long  to  appear  as  an  elevation,  as  the  rotation 
of  the  planet  would  carry  it  in  due  course  from 
the  position  r  to  the  position  s,  and  there  it 
would  be  forced  to  masquerade  as  a  depression. 
The  same,  reversely,  would  happen  to  a  val- 
ley. In  order  that  a  depression  should  appear 
continuously,  there  must  be  a  belt  of  lower 
level  along  its  circle,  and  this  could  not  be 
made  visible  as  in  the  former  case  by  projec- 
tion, since  projection  depends  upon  difference  of 
level  along  the  same  surface  contour,  not  as  be- 
tween adjacent  ones.  It  could,  therefore,  only 
be  noted  by  its  actual  profile,  —  a  very  small 
affair,  still  further  diminished  by  reason  of  the 
angle  under  which  that  profile  was  viewed. 
The  resulting  quantity  in  the  case  of  Mars 
would  be  exceedingly  minute.  We  perceive 
therefore,  on  the  very  threshold  of  our  inquiry, 
reason  to  doubt  the  mountainous  character  of 
the  irregularities.  Such  inference  becomes  the 
more  probable  on  a  more  detailed  investigation, 
into  which  we  will  now  enter.  This  investiga- 
tion depends  upon  a  very  important  principle  ; 
namely,  that  if  we  have,  as  in  this  case,  a  great 
number  of  observations,  it  is  possible,  by  divid- 
ing them  into  classes  according  to  their  kind  and 
then  taking  the  mean  value  of  each  class,  to 
discover  characteristics  not  otherwise  exposed. 

Means  are  very  telling  things.     They  are  so 
from  the  fact  of  simplifying  the  effects  of  the 


66  MARS 

factors  at  work.  By  taking  the  average  of  the 
series  of  observed  values  according  to  some  defi- 
nite principle,  not  only  do  we  eliminate  a  very 
large  class  of  errors,  but  we  allow  by  so  doing 
the  various  causes  to  unmask  their  separate 
results.  The  importance  of  reasoning  upon 
averages  could  hardly  be  more  strikingly  ex- 
emplified than  in  the  very  case  before  us,  —  that 
of  these  depressions  and  projections  seen  on  the 
terminator  of  Mars. 

Of  the  694  irregularities  measured,  291  were 
projections  and  403  were  depressions.  Here  at 
the  very  outset,  then,  we  perceive  an  objection 
to  the  theory  that  they  are  due  to  mountains ; 
to  wit,  because  the  number  of  depressions  so 
greatly  exceeds  the  number  of  projections.  As 
previously  explained  on  page  64,  mountains 
would  produce  on  the  average  as  many  projec- 
tions as  depressions,  for  they  would  project  the 
light  on  the  one  side  as  much  as  they  would 
cut  it  off  on  the  other. 

Now  let  us  classify  these  irregularities,  and 
see  if  we  can  gain  further  information  about 
them.  There  were  two  kinds  of  them,  —  the 
long  and  low,  and  the  short  and  sharp.  Each 
kind  had  its  representatives  among  both  the 
projections  and  the  depressions.  Of  the  short 
and  sharp  variety  there  were  95  projections. 
These  averaged  0.276  seconds  of  arc  in  height. 
Of  the  same  kind  there  were  similarly  57  depres- 


CLOUDS  67 

sions  which  averaged  0.368  seconds  of  arc  in 
depth.  It  will  be  noticed  then,  first,  that  the 
projections  of  this  character  exceeded  in  num- 
ber the  depressions  of  the  same  ;  secondly,  that 
the  average  depth  of  the  depressions  exceeded 
the  average  height  of  the  projections.  Now, 
if  the  appearances  had  been  due  to  mountains, 
both  the  number  and  size  of  the  projections 
and  of  the  depressions  should  have  been  sub- 
stantially the  same.  They  were  emphatically 
neither.  Consequently  mountains  fail  to  ex- 
plain them.  But  there  is  another  possible  set 
of  phenomena  that  will ;  namely,  clouds.  For, 
in  the  first  place,  clouds  would  cause  apparent 
depressions  and  projections,  since  the  light  would 
linger  on  them  as  it  does  on  mountain  tops,  and 
they  would  cast  shadows  as  mountains  do.  But 
furthermore  their  two  effects,  of  extending  or 
curtailing  the  limit  of  vision  along  the  termina- 
tor, would  not  necessarily  be  equal,  as  would  be 
the  case  with  hills.  Because  it  is  a  peculiarity 
of  mountains  that  they  are  attached  to  the  soil, 
and  are  commonly  permanencies ;  while  clouds 
are  not.  The  latter  form  and  dissipate,  dissi- 
pate and  re-form,  and  their  metamorphoses  are 
phenomena  depending  upon  the  time  of  day. 
Consequently  they  may  appear  in  one  place 
at  one  time,  in  another  the  next ;  and  what  is 
no  less  important,  they  may  form  at  different 
heights  at  different  times.  They  therefore  not 


68  MARS 

only  account  for  irregularities  on  the  termina- 
tor, but  they  account  also  for  irregularity  in  the 
plus  or  minus  character  of  these  irregularities. 
Clouds,  therefore,  are  capable  of  explaining  the 
case  before  us,  although  mountains  are  not. 

From  what  we  have  just  shown  let  us  mark 
now  just  what  clouds  are  here  required  to  ac- 
count for  what  we  see.  The  clouds  that  cause 
depressions  are  those  within  the  terminator, — 
those,  that  is,  that  form  before  sunset  or  after 
sunrise ;  while  those  that  cause  projections  are 
those  that  gather  after  sunset  or  before  sun- 
rise. As  the  observed  projections  in  this 
case  exceed  the  depressions  in  number,  we 
infer,  then,  that  there  are  more  clouds  after 
nightfall  than  before  it,  and  similarly  more 
before  daybreak  than  after  it ;  next,  as  the 
average  depression  is  greater  than  the  average 
projection,  we  likewise  infer  that  the  day  clouds 
lie  at  a  higher  altitude.  Now,  this  is  precisely 
what  we  should  expect  would  be  the  case,  just 
as  it  is  the  case  on  the  Earth. 

Of  the  other  class  of  irregularities,  the  long 
and  low,  there  were  observed  196  projections 
and  346  depressions.  The  projections  averaged 
0".136  in  height;  the  depressions,  0".125  in 
depth.  Here,  then,  we  have  an  opposite  state  of 
things  from  that  with  which  we  were  confronted, 
in  the  short  and  sharp  class.  Here,  as  compared 
with  the  projections,  instead  of  relatively  few 


CLOUDS  69 

depressions  of  greater  height,  we  have  rela- 
tively many  depressions  of  less  height.  Fur- 
thermore, there  are  a  great  many  more  of  both 
projections  and  depressions  than  there  were  of 
the  former  variety,  and  they  are  both  of  much 
less  height  or  depth.  Evidently,  therefore,  we 
have  here,  in  part  at  least,  a  different  class  of 
phenomena  from  what  we  have  previously  con- 
sidered. Now  we  perceive  at  once  that  two 
factors  enter  here  which  did  not  enter  in  the 
case  of  the  short  and  sharp  irregularities.  The 
long  and  low  depressions  occur,  as  we  shall  re- 
call, almost  always  over  the  dark  areas,  while 
the  short  and  sharp  ones  do  not.  In  the  next 
place,  the  average  height  or  depth  of  the  long 
and  low  irregularities  is  much  nearer  the  value 
of  the  irradiation  constant,  that  is,  the  amount 
by  which  a  bright  object  seems  bigger  on  ac- 
count of  its  brightness ;  which  would  cause  the 
dark  areas  to  seem  depressed.  From  these  facts 
we  infer  that  most  of  the  depressions  of  this 
class  are  due  to  the  character,  not  to  the  con- 
tour, of  the  surface  where  they  occur ;  partly  to 
the  direct  effect  of  lack  of  irradiation,  partly 
to  sombreness  of  the  surface,  which  would  cause 
the  light  to  fade  from  them  at  a  greater  relative 
distance  from  the  terminator.  On  eliminating 
these  depressions,  therefore,  we  find  ourselves 
left  with  very  few  depressions  as  against  nearly 
200  projections.  The  excess  in  number  of  the 


70  MARS 

latter  shows,  as  in  the  case  of  the  other  variety, 
that  we  are  here  dealing  chiefly  with  long  and 
relatively  low  clouds  formed  after  sunset  or  be- 
fore sunrise;  those  so  formed  during  daylight 
being  few  if  any. 

One  more  observation  made  at  Flagstaff,  on 
the  subject  of  cloud,  is  as  peculiar  as  it  is 
important.  It  was  made  by  Mr.  Douglass,  and 
I  shall  give  it  in  his  own  words.  A  more  de- 
tailed account  of  it,  together  with  his  tables  of 
figures,  will  appear  in  his  paper  upon  it  in  the 
Observatory  annals :  — 

"  On  November  25  and  26  a  bright  spot  was 
seen  in  the  unilluminated  portion  of  Mars,  to 
which,  in  my  opinion,  no  other  name  than  cloud 
can  be  applied.  Its  great  height,  size,  and  bril- 
liancy, and,  on  the  second  evening,  its  singu- 
lar fluctuations,  render  it  of  importance  in  the 
study  of  the  Martian  atmosphere. 

"  I  first  saw  it  at  16h.  35m.,  G.  M.  T.,  of  No- 
vember 25,  and  made  an  estimate  of  its  height. 
It  seemed  to  be  rapidly  increasing  in  length  in 
a  direction  parallel  to  the  terminator  at  that 
point.  Subsequent  estimates  of  its  height  gave 
a  different  and  greater  value  than  at  first,  until 
its  sudden  disappearance  at  17h.  6m.,  or  perhaps 
a  minute  later.  After  once  attaining  its  size,  it 
seemed  to  remain  with  little  change,  presenting 
the  appearance  of  a  line  115  miles  long  by  33 
miles  wide  at  the  centre  and  lying  parallel  to 


CLOUDS  71 

the  terminator,  but  separated  from  it  by  an  ap- 
parent space  of  over  80  miles.  It  was  gener- 
ally yellowish  in  color,  like  the  limb,  but  of  less 
brilliancy  than  the  centre  of  the  disk,  though 
distinctly  surpassing  in  that  respect  the  adja- 
cent terminator.  I  estimated  it  to  have  the 
brilliancy  of  the  bright  areas  of  the  disk  at  a 
distance  of  9°  from  the  terminator.  In  one 
view  it  appeared  to  be  a  very  small  whitish 
point,  and  I  am  inclined  to  think  that  there 
may  have  been  a  real  diminution  in  its  size  at 
that  moment.  This  idea  is  partly  sustained  by 
the  following  night's  observations.  At  16h. 
54m.  it  was  observed  by  Professor  Pickering, 
whose  estimate  gave  11  miles  for  its  height.  At 
17h.  5m.,  after  obtaining  two  readings  of  the 
micrometer  screw  for  latitude,  the  seeing,  which 
had  been  quite  steadily  at  the  figure  7  (on  a 
scale  of  10),  dropped  to  4,  and  in  attempt- 
ing the  next  setting  I  could  not  find  the 
1  cloud,'  although  once  before  it  had  remained 
visible  when  the  seeing  dropped  instantaneously 
to  that  figure.  Nor  did  it  reappear  in  the  next 
half  hour.  This  sudden  disappearance,  without 
any  previous  lessening  of  its  height  above  the 
terminator  or  of  its  size,  made  its  cloud  charac- 
ter unmistakable,  since  a  mountain  beyond  the 
sunrise  terminator  must  either  constantly  de- 
crease in  height,  or  soon  join  the  illuminated 
disk. 


72  MARS 

"  A  subsequent  computation  showed  that  this 
phenomenon  took  place  over  the  southern  part 
of  Schiaparelli's  Protei  Regio.  Other  reasons 
lead  me  to  think,  however,  that  he  has  placed 
that  island  some  5°  too  far  south. 

"  On  November  26  the  cloud  promptly  ap- 
peared at  17h.  15m.,  G.  M.  T.,  but  about  12°  far- 
ther north.  Instead  of  remaining  continuously 
visible,  it  dissipated  and  reformed  at  irregular 
intervals.  The  first  appearance  lasted  sixteen 
minutes.  After  somewhat  over  four  minutes 
had  passed,  it  reappeared  momentarily,  and  six 
minutes  elapsed  before  it  appeared  again,  lasting 
then  but  two  and  one  half  minutes.  Then  fol- 
lowed an  absence  of  three  minutes,  presence  for 
two  minutes,  absence  for  three  minutes,  presence 
for  one  minute,  and  a  final  brief  appearance 
eight  minutes  later  at  18h.  1m.  Its  presence 
was  suspected  five  minutes  before  that  hour, 
and  again  at  18h.  llm.,  but  with  great  uncer- 
tainty. 

"  At  this  time  it  presented  in  general  the 
same  characteristics  as  the  night  before,  though 
its  appearances  were  too  brief  to  permit  such 
careful  observations  as  were  hoped  for.  The 
seeing,  too,  was  not  so  good  as  before,  varying 
from  4  to  7 ;  and  if  the  cloud  happened  to  ap- 
pear under  the  former  figure,  its  observation 
was  difficult.  It  is  needless  to  remark  that 
under  such  conditions  it  was  impossible  to  ob- 


CLOUDS  73- 

serve  its  appearance  or  disappearance  to  the 
second.  In  general,  it  seemed  to  exhibit  a  less 
elevation  than  the  night  before.  A  careful 
estimate  of  its  latitude  placed  it  precisely  at  the 
centre  of  the  terminator.  I  believe  these  lati- 
tude observations,  though  made  rapidly,  cannot 
be  subject  to  an  error  greater  than  2°,  and  prob- 
ably less  than  1°.  On  November  27,  at  18h.,  I 
searched  for  the  cloud,  but  was  not  rewarded  by 
finding  any  trace  of  it. 

"  Estimates  of  the  size  and  height  of  this 
cloud  were  made  with  reference  to  a  glass 
thread  in  the  micrometer,  whose  diameter  is 
0".6.  One  tenth  of  the  thread  was  found  to  rep- 
resent on  Mars  a  little  less  than  twenty  miles. 
This  gives  us  an  elevation  above  the  surface  of 
between  10  and  11  miles.  In  this  process  we 
have  taken  the  apparent  centre  of  the  cloud, 
and  have  assumed  the  seeing  to  have  no  influ- 
ence. We  obtain,  therefore,  the  smallest  possi- 
ble mean  height  of  the  centre  of  the  cloud.  If 
we  assume  that  the  seeing  was  not  perfect,  its 
effect  would  be  to  lessen  the  separation,  but  not 
to  change  the  total  height.  Supposing,  for  ex- 
ample, that  the  apparent  extension  of  the  cloud 
was  due  to  poor  seeing  enlarging  a  point,  then 
our  terminator  distance  would  be  245  miles, 
and  our  minimum  elevation  15  miles.  There- 
fore we  can  assume  15  miles  to  be  the  smallest 
probable  mean  elevation  of  this  cloud.  The 


74  MARS 

average  height  of  our  cirrus  clouds  is  five  and 
one  half  miles. 

"One  more  idea  requires  mention,  namely, 
the  movement  of  this  cloud  in  latitude.  From 
the  extreme  rarity  of  clouds  on  Mars  I  am  in- 
clined to  connect  intimately  the  appearances  of 
the  two  evenings,  and  consider  them  as  due  to 
one  source,  presumably  a  large  body  of  air  mov- 
ing northward.  Such  an  advance  would  be  at 
the  rate  of  18.7  miles  per  hour." 

I  may  add  to  this  that  the  height  of  the 
cloud  —  relatively  to  those  of  the  Earth  —  is 
what  direct  deduction  from  the  less  rapid  thin- 
ning out  of  the  air  above  the  Martian  surface, 
which  must  result  from  the  smaller  mass  of 
Mars,  would  lead  us  to  expect.  The  air  at  the 
surface  would  be  thinner  than  at  the  surface 
of  the  Earth,  but  the  rate  at  which  it  diminished 
with  the  height  above  that  surface  would  not  be 
so  great.  At  no  very  great  elevation  the  two 
densities  would  come  to  be  the  same. 

One  deduction  from  this  thin  air  we  must 
be  careful  not  to  make  —  that  because  it  is  thin 
it  is  incapable  of  supporting  intelligent  life. 
That  beings  constituted  physically  as  we  are 
would  find  it  a  most  uncomfortable  habitat  is 
pretty  certain.  But  lungs  are  not  wedded  to 
logic,  as  public  speeches  show,  and  there  is 
nothing  in  the  world  or  beyond  it  to  prevent,  so 
far  as  we  know,  a  being  with  gills,  for  example, 


CLOUDS  75 

from  being  a  most  superior  person.  A  fish  doubt- 
less imagines  life  out  of  water  to  be  impossible  ; 
and  similarly  to  argue  that  life  of  an  order 
as  high  as  our  own,  or  higher,  is  impossible 
because  of  less  air  to  breathe  than  that  to 
which  we  are  locally  accustomed,  is,  as  Flamma- 
rion  happily  expresses  it,  to  argue,  not  as  a 
philosopher,  but  as  a  fish. 

To  sum  up,  now,  what  we  know  about  the 
atmosphere  of  Mars :  we  have  proof  positive 
that  Mars  has  an  atmosphere ;  we  have  reason 
to  believe  this  atmosphere  to  be  very  thin,  — 
thinner  at  least  by  half  than  the  air  upon  the 
summit  of  the  Himalayas,  —  and  in  constitution 
not  to  differ  greatly  from  our  own. 


WATER 
I.     THE   POLAR   CAP 

AFTER  air,  water.  If  Mars  be  capable  of 
supporting  life,  there  must  be  water  upon  his 
surface ;  for,  to  all  forms  of  life,  water  is  as  vital 
a  matter  as  air.  On  the  question  of  habitabil- 
ity,  therefore,  it  becomes  all-important  to  know 
whether  there  be  water  on  Mars. 

To  the  solution  of  this  inquiry,  also,  the 
planet's  polar  cap  turns  out  to  hold  the  key. 
For  just  as  the  fact  of  change  in  the  cap  proves 
the  presence  of  air,  so  the  manner  of  that 
change  implies  the  presence  of  water.  It  not 
only  does  this ;  it  turns  out  to  do  a  deal  more. 
For  to  the  whole  water  question  it  appears  to 
play  the  part  not  only  of  occasion  but  of  cause. 
In  more  senses  than  one,  it  is  in  that  great 
glistening  white  patch  that  our  water  problem 
takes  its  rise. 

On  the  3d  of  June,  1894,  the  south  polar  cap 
stretched,  almost  one  unbroken  waste  of  white, 
over  about  55  degrees  of  latitude.  A  degree 
on  Mars  measures  37  miles;  consequently  the 


THE  POLAR  CAP  77 

cap  was  2,035  miles  across.  /Inasmuch  as  the 
inclination  of  the  Martian  Equator  to  the  plane 
of  the  Martian  orbit  is,  according  to  Schiapa- 
relli,  24°  52',  it  must  have  then  covered  more 
than  the  whole  south  frigid  zone  of  the  planet. 

Now,  to  take  in  the  full  meaning  of  the  con- 
dition of  the  cap  at  this  time  and  of  the  changes 
that  ensued,  we  must  begin  by  determining  the 
Martian  time  of  year.  This  is  done  by  fixing 
the  dates  at  which  the  Martian  pole  reached 
its  maximum  tilt  toward  or  from  the  Sun,  and 
the  dates  at  which  it  was  not  tilted  either  to 
or  from,  but  sideways  to,  the  Sun ;  the  former 
gives  us  the  Martian  solstices,  and  the  latter 
the  Martian  equinoxes.  It  thus  appears  that 
on  April  7,  1894,  occurred  the  vernal  equinox 
of  the  Martian  southern  hemisphere,  on  August 
31,  its  summer  solstice,  and  on  February  7, 
1895,  its  autumnal  equinox.  From  these  dates 
it  is  easy  to  transform  the  one  calendar  into  the 
other.  On  the  3d  of  June,  1894,  therefore,  it 
was  about  May  1  on  the  southern  hemisphere 
of  Mars. 

On  May  1,  then,  Martian  time,  the  cap  was 
already  in  rapid  process  of  melting ;  and  the 
speed  with  which  it  proceeded  to  dwindle 
showed  that  hundreds  of  square  miles  of  it  were 
disappearing  daily.  As  it  melted,  a  dark  band 
appeared  surrounding  it  on  all  sides.  Except,  as 
I  have  since  learned,  at  Arequipa,  this  band  has 


78  MARS 

never,  I  believe,  been  distinctively  noted  or 
commented  on  before,  which  is  singular,  con- 
sidering how  conspicuous  it  was  at  Flagstaff. 
It  is  specially  remarkable  that  it  should  never 
have  been  remarked  upon  elsewhere,  in  that 
a  similar  one  girdling  the  north  polar  cap  was 
seen  by  Beer  and  Madler  as  far  back  as  1830. 
For  it  is,  as  we  shall  shortly  see,  a  most  signifi- 
cant phenomenon.  In  the  first  place,  it  was  the 
darkest  marking  upon  the  disk,  and  was  of  a 
blue  color.  It  was  of  different  widths  at  differ- 
ent longitudes,  and  was  especially  pronounced 
in  tint  where  it  was  widest,  notably  in  two 
spots  where  it  expanded  into  great  bays,  one  in 
longitude  270°  and  one  in  longitude  330°.  The 
former  of  these  was  very  striking  for  its  color, 
a  deep  blue,  like  some  other-world  grotto  of 
Capri.  The  band  was  bounded  on  the  north, 
that  is,  on  the  side  toward  the  equator,  by  the 
bluish-green  areas  of  the  disk.  It  was  con- 
trasted with  these  both  in  tone  and  tint.  It 
was  both  darker  and  more  blue. 

The  band  not  only  varied  in  width  at  differ- 
ent longitudes,  but  its  width  corresponded  to 
the  amount  of  the  blue-green  areas  of  the  disk 
visible  at  these  longitudes  below  it.  It  was 
widest  where  these  were  greatest  in  extent,  and 
narrowest  where  they  were  least.  If  we  con- 
sult the  map  of  Mars  we  shall  see  that  below 
the  bay  in  longitude  330°  lies  the  great  dark 


THE  POLAR  CAP  79 

area,  the  Syrtis  Major,  and,  below  the  one  in 
longitude  270°,  the  Syrtis  Minor.  This  corre- 
lation was  highly  suggestive  in  itself.  As  if, 
however,  to  remove  all  question  as  to  possible 
coincidence  having  a  hand  in  the  matter,  the 
agreement  in  position  was  emphasized  by  visi- 
ble connection.  Two  long  dark  streaks  appeared 
joining  respectively  each  bay  to  its  correspond- 
ing Syrtis. 

But  the  most  significant  fact  about  the  band 
was  that  it  kept  pace  with  the  polar  cap's  re- 
treat toward  the  pole.  As  the  white  cap  shrank 
it  followed  pari  passu  so  as  always  to  border 
the  edge  of  the  snow.  It  thus  showed  itself 
not  to  be  a  permanent  marking  of  the  planet's 
surface,  since  it  changed  its  place,  but  a  tempo- 
rary one,  dependent  directly  upon  the  waning 
of  the  cap  itself.  In  short,  it  was  an  associated 
detail,  and  itself  instantly  suggested  its  charac- 
ter, namely,  that  it  was  water  at  the  edge  of 
the  cap  due  to  the  melting  of  the  polar  snow. 

Not  only  did  the  band  conform  with  the  cap 
in  position;  it  did  so  in  size.  As  the  snows 
dwindled,  the  blue  band  about  them  shrank  in 
width  to  correspond.  By  August  it  was  a 
barely  discernible  thread  drawn  round  the  tiny 
white  patch  which  was  all  that  remained  of  the 
enormous  snow-fields  of  some  months  before. 
Finally,  on  October  13,  when  the  snow  entirely 
disappeared,  as  we  shall  presently  see,  the  spot 


80  MARS 

where  it  and  its  girdle,  long  since  grown  too 
small  for  detection,  had  been  became  one  yellow 
stretch. 

That  the  blue  was  water  at  the  edge  of  the 
melting  snow  seems  unquestionable.  That  it 
was  the  color  of  water ;  that  it  so  persistently 
bordered  the  melting  snow ;  and  that  it  subse- 
quently vanished,  are  three  facts  mutually  con- 
firmatory to  this  deduction.  But  a  fourth  bit 
of  proof,  due  to  the  ingenuity  of  Professor  W. 
H.  Pickering,  adds  its  weight  to  the  other  three. 
For  he  made  the  polariscope  tell  the  same  tale. 
On  scrutinizing  the  great  bay  through  an  Arago 
polariscope,  he  found  the  light  coming  from  the 
bay  to  be  polarized.  Now,  to  polarize  the  light 
it  reflects  is  a  property,  as  we  know,  of  a  smooth 
surface  such  as  that  of  water  is. 

Before  going  further  we  will  take  up  here 
at  the  outset  the  question  of  the  constitution 
of  these  polar  caps,  which  in  their  general  be- 
havior so  strikingly  suggest  our  own  ice-caps  as 
they  would  appear  could  they  be  seen  from  a 
distance  of  forty  millions  of  miles.  That  they 
so  instantly  suggest  snow  has  suggested,  to  that 
class  of  mind  which  likes  to  make  of  molehills 
of  question  mountains  of  doubt,  the  possibility 
that  instead  of  ice  we  have  here  snow-caps  of 
solid  carbonic  acid  gas  (carbon  dioxide).  The 
occasion  of  the  suggestion  is  the  fact  that  car- 
bonic dioxide  under  certain  conditions  becomes 


THE  POLAR  CAP  81 

a  colorless  liquid,  and  then  a  solid  of  a  floccular, 
snow-like  character.  It  assumes,  in  short,  under 
proper  conditions  of  pressure  and  cold,  the  va- 
rious appearances  presented  by  water  under 
higher  temperatures,  although  it  does  so  with 
very  different  degrees  of  ease.  Superficially, 
therefore,  the  idea  seems  plausible.  Let  us  see 
if  it  still  seems  so  when  critically  examined. 

Faraday  made  experiments  on  the  relation  of 
the  congealing  point  of  carbonic  acid  gas  to  the 
pressure,  and  found  that  at  0°  C.  it  took  a  pres- 
sure of  36  atmospheres,  that  is,  540  pounds  to 
the  square  inch,  to  solidify  the  gas,  and  that  at 
— 99°  C.,  the  lowest  temperature  with  which  he 
experimented,  it  took  1.14  atmospheres.  At 
this  point  the  curve  representing  the  relation 
was  becoming  apparently  asymptotic,  that  is, 
a  slight  decrease  in  pressure  involved  a  great 
falling  off  of  temperature.  Under  a  pressure 
of  one  atmosphere,  therefore,  the  temperature 
would  be  about  — 170°  F.,  that  is,  on  the  surface 
of  the  Earth  this  would  be  the  congealing  point 
of  the  gas. 

He  found  further  that  the  curve  for  the  lique- 
faction point  lay  very  close  to  that  for  the  con- 
gealing point,  and  approached  yet  closer  as  the 
pressure  decreased.  In  other  words,  the  gas 
passed  almost  immediately  from  the  gaseous  to 
the  solid  state. 

In  the  light  of  these  facts  let  us  consider  the 


82  MARS 

condition  of  Mars.  Three  points  arise  which 
we  will  take  in  the  inverse  order  of  their  im- 
portance. First :  the  appearance  of  the  planet 
shows  conclusively  that,  if  the  polar  caps  be 
composed  of  solid  carbonic  acid  gas,  then  either 
there  is  no  water  at  all  on  Mars  in  any  form 
whatsoever,  or  what  there  is  is  ice  so  overlaid 
with  detritus  as  to  be  invisible.  For  if  the  two 
substances  were  there  together,  and  the  cold  at 
the  surface  of  the  planet  of  so  extreme  a  char- 
acter as  to  congeal  the  carbon  dioxide,  the  water 
must  a  fortiori  be  frozen,  and  would  continue  so 
long  after  the  temperature  rose  above  the  melt- 
ing point  of  the  former  substance.  We  should 
therefore  still  have  snow-fields  of  snow  after  the 
melting  of  those  formed  of  carbonic  acid  gas, 
either  visible  as  white  patches  or  so  covered  up 
with  dirt  as  to  pass  for  land.  Now  there  are  no 
such  additional  white  patches  to  be  seen,  nor,  so 
far  as  we  can  judge,  does  any  part  of  the  planet 
behave  as  if  it  were  glacier-bound. 

Second :  carbonic  dioxide  passes,  as  we  saw, 
almost  simultaneously  into  the  liquid  and  solid 
states,  especially  under  slight  pressure.  Now, 
the  pressure  is  certainly  very  slight  on  the 
surface  of  Mars ;  not  probably  more  than,  and 
probably  less  than,  one  seventh  of  an  atmosphere. 
In  consequence,  on  a  rise  of  temperature  the 
frozen  carbonic  acid  gas  would  there  pass  prac- 
tically straight  from  the  solid  into  the  gaseous 


THE  POLAR  CAP  83 

state.  Now,  from  the  existence  of  the  surround- 
ing polar  sea,  we  remark  that  in  the  substance 
composing  the  polar  caps  of  Mars  this  does  not 
occur.  A  considerable  portion  of  it  is  always 
in  the  transition  state  of  a  liquid.  Carbonic  di- 
oxide would  not  thus  tarry  :  water  would. 

Third  :  from  the  curve  of  metamorphosis,  it  is 
evident  that  the  temperature  necessary  to  freeze 
the  gas  under  the  pressure  of  one  seventh  of  an 
atmosphere  must  lie  between  — 100°  C.  and 
—200°  C.,  if  not  lower.  —200°  C.  is,  so  far  as 
we  can  judge,  about  the  temperature  of  inter- 
planetary space,  or  what  would  be  the  tempera- 
ture of  the  night  side  of  Mars  were  the  planet 
destitute  of  atmosphere.  But  there  is  an  atmos- 
phere on  Mars,  and,  even  if  there  were  not,  on 
melting  the  carbonic  dioxide  would  itself  make 
an  atmosphere.  This  would  instantly  raise  the 
temperature,  and  under  any  rise  in  temperature 
the  congealing  of  the  gas  at  once  becomes  an 
impossibility.  The  gas  itself  thus  suggests  its 
own  refutation. 

There  is  no  such  apparent  objection  to  water. 
With  an  atmosphere  properly  constituted  (and 
there  is  nothing  to  show  that  the  Martian  at- 
mosphere is  not  so  constituted),  the  tempera- 
ture might  easily  rise  high  enough  to  melt  ice. 
We  may  therefore  conclude  water  to  be  the 
most  probable  solution  of  the  question. 

With  such    more   or   less   solid    ground    to 


84  MARS 

stand  on,  we  may  now  go  on  to  describe  the 
behavior  of  the  cap  as  constituted  of  snow. 
Whether  we  call  it  snow-cap  or  ice-cap  is  im- 
material, as,  although  it  would  probably  be 
deposited  as  hoar-frost  rather  than  as  snow  in 
the  first  instance,  owing  to  the  thinness  of  the 
Martian  air,  the  latter  end  of  either  form  of  the 
substance  would  be  much  the  same,  —  glacier- 
ice. 

It  will  be  interesting  to  examine  more  in  de- 
tail the  annual  history  of  the  ice-cap,  especially 
as  this  history  was  unrolled  before  us  last  year 
more  minutely  than  has  been  the  case  for  the 
last  fifteen  years,  and  than  will  be  the  case  for 
fifteen  years  to  come.  This  was  due  not  only 
to  the  relative  proximity  of  the  planet  during 
the  last  opposition,  but  to  the  further  fact 
that  its  south  pole  was  tilted  toward  us  at  a 
maximum  angle.  The  vicissitudes  which  the 
polar  cap  underwent  stood,  in  consequence,  re- 
markably well  displayed.  To  such  advantage 
were  they  seen  that  it  has  been  possible  to  con- 
struct a  map  of  the  Martian  south  circumpolar 
regions  to  a  degree  of  detail  such  as  has  never 
been  possible  before,  and  which  I  have  accord- 
ingly done.  It  will  be  seen  from  it  (on  the 
opposite  page)  how  much  farther  advanced  is 
our  knowledge  of  the  Martian  south  pole,  and 
the  regions  about  it,  than  is  our  knowledge  of 
either  of  our  own.  It  is  also  pleasing  to  re- 


230*. 


MAP  OF  THE    SOUTH   POLE   OF  MARS 
SHOWING  THE  POLAR  CAP  AND  ITS  CHANGES  IN  1894 


THE  POLAR  CAP  85 

member  that  during  this  our  polar  expedition 
we  were  not  frost-bitten  for  life,  nor  did  we 
have  to  be  rescued  by  a  search  party.  We  lived 
,not  unlike  civilized  beings  during  it  all,  and  we 
actually  brought  back  some  of  the  information 
we  went  out  to  acquire. 

On  examining  the  chart  in  which  the  succes- 
sive appearances  of  the  southern  ice-cap  are  de- 
picted at  different  times,  from  June  3  to  October 
13,  or,  in  terms  of  the  Martian  time  of  year,  from 
May  1  to  July  15,  the  first  point  to  strike  one  is 
that  the  cap  was  during  its  whole  existence  ec- 
centrically placed  with  regard  to  the  geograph- 
ical pole  of  the  planet.  In  other  words,  the  pole 
of  rotation  and  the  pole  of  cold  did  not  coincide. 
The  latter  lay  on  the  average  some  six  degrees 
distant  from  the  former.  This  shows  that  the 
isotherms  in  the  southern  hemisphere  of  Mars 
do  not  coincide  with  the  parallels  of  latitude. 

The  manner  of  the  cap's  melting  further 
shows  that  differences  of  level  exist  in  it.  For, 
in  addition  to  melting  round  its  edge,  the  cap 
proceeded  to  melt  asymmetrically.  On  the  first 
night  that  Professor  W.  H.  Pickering  observed 
it,  on  May  22,  with  the  six-inch  telescope,  he 
suspected  a  rift  crossing  the  cap  from  longitude 
330°  to  longitude  170°.  This  rift  grew  more 
and  more  evident,  until,  in  the  early  part  of 
June,  it  was  unmistakable.  It  grew  in  visibility 
chiefly  from  actual  growth  in  size.  On  June  6 


86  MARS 

it  was  estimated,  on  a  scale  of  ruled  lines  made 
for  the  purpose,  to  be  about  100  miles  wide. 
On  June  15  it  was  similarly  found  to  measure 
220  miles. 

Meanwhile  an  interesting  phenomenon  oc- 
curred in  the  cap  on  June  7.  On  that  morn- 
ing, at  about  a  quarter  of  six  (or,  more  precisely, 
on  June  8,  Ih.  17m.,  G.  M.  T.),  as  I  was  watch- 
ing the  planet,  I  saw  suddenly  two  points  like 
stars  flash  out  in  the  midst  of  the  polar  cap. 
Dazzlingly  bright  upon  the  duller  white  back- 
ground of  the  snow,  these  stars  shone  for  a  few 
moments  and  then  slowly  disappeared.  The 
seeing  at  the  time  was  very  good.  It  is  at 
once  evident  what  the  other-world  apparitions 
were,  —  not  the  fabled  signal-lights  of  Martian 
folk,  but  the  glint  of  ice-slopes  flashing  for 
a  moment  earthward  as  the  rotation  of  the 
planet  turned  the  slope  to  the  proper  angle ; 
just  as,  in  sailing  by  some  glass-windowed  house 
near  set  of  sun,  you  shall  for  a  moment  or  two 
catch  a  dazzling  glint  of  glory  from  its  panes, 
which  then  vanishes  as  it  came.  But  though 
no  intelligence  lay  behind  the  action  of  these 
lights,  they  were  none  the  less  startling  for 
being  Nature's  own  flash-lights  across  one  hun- 
dred millions  of  miles  of  space.  It  had  taken 
them  nine  minutes  to  make  the  journey ;  nine 
minutes  before  they  reached  Earth  they  had 
ceased  to  be  on  Mars,  and,  after  their  travel  of 


THE  POLAR  CAP  87 

one  hundred  millions  of  miles,  found  to  note 
them  but  one  watcher,  alone  on  a  hill-top  with 
the  dawn. 

Calculation  showed  the  position  of  the  star- 
points  to  be  in  longitude  280°  and  290°  and 
in  latitude  76°  south.  At  this  place  on  the 
planet,  then,  there  was  a  range  of  slopes  suffi- 
ciently tilted  to  reflect  the  Sun  from  their  ice- 
clad  sides.  On  comparing  its  position  with 
Green's  map  of  his  observations  upon  the  cap 
at  Madeira  in  1877,  it  appeared  that  this  was 
the  identical  position  of  the  spot  where  he  had 
seen  star-points  then,  and  where  Mitchell  had 
seen  them  in  1846,  to  whom  they  had  suggested 
the  same  conclusion.  Green  christened  them 
the  "  Mitchell  Mountains."  At  the  times  both 
these  observers  saw  them,  they  were  detached 
from  the  rest  of  the  cap.  At  the  time  of  this 
observation  in  June,  they  were  still  in  the  midst 
of  the  cap.  We  shall  see  that  they  eventually 
became  islands,  just  as  Green  saw  them,  and 
that  the  observation  in  June  marked  an  earlier 
stage  in  their  history. 

On  June  10  Mr.  Douglass  detected  a  second 
rift  in  the  cap  backing  the  range  of  slopes. 
And  on  June  13  I  noticed  that  behind  the 
bright  points  the  snow  fell  off  shaded  to  this 
rift.  Meanwhile  a  third  rift  had  been  made 
out  by  him,  running  from  longitude  170°  to 
longitude  90°,  —  very  nearly,  therefore,  at  right 


88  MARS 

angles  to  the  first  rift  and  debouching  into  it. 
Bright  points  continued  to  be  seen  at  various 
points  to  the  westward  round  the  cap.  They 
are  marked  by  crosses  on  the  chart.  Through- 
out these  days,  the  cap  was  wont  to  appear 
shaded  upon  the  terminator  side,  as  one  might 
expect  of  a  snow  or  ice  slope.  During  June, 
also,  the  contour  of  the  cap  was  apparently 
elliptical.  But  on  June  25  Professor  W.  H. 
Pickering  noted,  for  the  first  time,  that  it  no 
longer  looked  so.  The  melting  had  resulted  in 
making  its  asymmetry  perceptible. 

On  July  1  our  Martian  polar  expedition  dis- 
closed what  used  to  be  the  supreme  quest  of 
earthly  expeditions,  —  that  dream  of  arctic  ex- 
plorers, an  open  polar  sea.  On  that  day  Pro- 
fessor Pickering  perceived,  in"  the  midst  of  the 
cap,  in  longitude  260°  and  latitude  80°,  a  sheet 
of  water  about  250  miles  long  by  150  broad.  It 
was  in  fact  the  spreading  of  the  first  rift  about 
midway  across  the  cap,  and  lay  not  far  from 
the  geographical  pole  of  the  planet,  though  not, 
it  is  to  be  noticed,  near  the  pole  of  cold,  for  it 
lay  on  the  further  side  of  the  geographical  pole 
from  it.  There  is  a  touch  of  the  irony  of  fate 
in  this  detection  of  an  open  polar  sea  on  Mars 
before  explorers  have  succeeded  in  doing  so  on 
the  Earth. 

In  addition  to  these  rifts  and  other  irregu- 
larities of  melting,  small  detached  bits  of  the 


THE  POLAR  CAP 

cap  showed  from  time  to  time,  one  being  seen 
by  Professor  Pickering  on  July  9  in  longitude 
284°,  and  another  by  him  on  July  23  in  about 
longitude  160°. 

Meanwhile  the  cap  had  been  steadily  decreas- 
ing in  size,  its  progressive  diminutions  being 
shown  on  the  map  in  the  successive  contour 
lines.  The  polar  sea  faithfully  followed  it  in 
its  shrinkage,  even  the  bays  keeping  their  longi- 
tudes unchanged.  But,  whereas  early  in  June 
the  bay  at  longitude  270°  had  been  blue,  it  now 
appeared  brown;  of  that  mud-color  land  does 
from  which  the  water  has  recently  been  drained 
off. 

After  various  vicissitudes,  too  numerous  to 
mention  in  detail,  on  August  6  a  separate 
patch  of  snow  showed  very  conspicuous,  to  the 
left  of  the  main  body.  The  smaller  detachment 
lay  in  longitude  290°,  and  in  latitude  75°-78°. 
Now,  on  turning  to  the  record  of  the  star-points 
that  had  appeared  two  months  before,  it  will  be 
seen  that  this  was  their  position.  Here,  then, 
was  proof  of  the  identity  of  the  star-points  seen 
in  June  with  the  islands  recorded  by  Mitchell 
and  Green.  The  detached  patch  was  in  fact 
the  range  of  slopes  left  in  isolated  insularity 
after  all  about  it  had  melted  away.  From  this 
we  have  an  interesting  bit  of  corroborative  testi- 
mony that  it  stood  on  higher  ground. 

On  August  11  the  detached  patch  was  yet 


90  MARS 

farther  separated  from  the  main  body  of  the 
cap,  the  smaller  patch  being  many  degrees  dis- 
tant to  the  north  of  either  the  geographical 
pole  or  the  pole  of  cold,  with  water  and  even 
dry  land  to  the  south  of  it.  It  will  be  remem- 
bered, for  the  points  of  the  compass,  that  this  is 
the  southern  hemisphere  of  which  we  are  speak- 
ing, and  that,  for  climatic  purposes,  north  and 
south  here  stand  interchanged.  On  August  13 
the  detached  patch  is  recorded  for  the  last  time, 
or,  in  other  words,  about  this  time  it  melted 
away.  The  larger  one  remained,  contracting 
in  size,  however,  as  time  went  on.  So  it  con- 
tinued through  August,  September,  and  well 
into  October. 

On  October  12,  at  lOh.  40m.,  I  made  the  fol- 
lowing entry  about  it :  "  Polar  cap  has  been 
very  faint  for  some  time  ;  barely  visible."  At 
13h.  26m.,  or,  in  other  words,  at  about  half 
past  one  that  night,  Mr.  Douglass  measured  its 
position  and  estimated  its  size,  as  was  his  wont 
every  few  days.  He  found  it  to  be  six  degrees 
distant  from  the  planet's  pole,  in  longitude  54°. 
The  patch  was  very  small,  covering  about  one 
hundred  and  fifty  miles  square.  On  looking 
at  the  planet  on  October  13,  at  8h.  15m.,  to 
his  surprise  he  found  the  cap  gone.  Not  a 
trace  of  it  could  be  seen ;  nor  could  either 
he  or  I  detect  it  during  the  rest  of  that  night, 
although  such  was  the  longitude  of  the  central 


THE  POLAR  CAP  91 

meridian  throughout  it  as  to  bring  the  cap  on 
the  nearer  side  of  the  pole,  and  therefore  show 
it  to  best  advantage.  What  had  certainly  been 
there  on  the  12th  was  not  there  on  the  13th. 
The  ice-cap  had  disappeared. 

No  such  occurrence  has  ever  been  chronicled 
before.  It  is  the  first  time  since  man  began  to 
observe  the  planet  that  the  ice-cap  has  com- 
pletely disappeared.  Hitherto  it  has  been  seen 
to  diminish  to  a  minimum  of  from  7°  to  4°,  and 
then  begin  to  increase  again.  This  last  autumn, 
for  the  first  time,  it  vanished  entirely.  The 
date  of  this  occurrence  was,  in  Martian  chro- 
nology, about  July  20.  Evidently,  for  some 
reason  unknown  to  us,  it  was  a  phenomenally 
hot  season  in  the  southern  hemisphere  of  the 
planet. 

Practically  it  never  reappeared  again  during 
the  season.  That  it  did  return  occasionally,  as 
a  very  small  speck,  was  from  time  to  time  sus- 
pected, and  doubtless  did  take  place.  Certainly 
it  left  for  some  time  behind  it  a  glimmer  where 
it  had  been,  due  presumably  to  the  moisture 
from  its  melting,  still  tarrying  on  the  ground 
or  lingering  in  the  air.  Otherwise,  to  all  intents 
and  purposes,  where  the  polar  ice-cap  and  polar 
sea  had  been  was  now  one  ochre  stretch  of 
desert. 

Having  thus  followed  to  its  vanishing  point 
the  polar  cap,  we  will  now  return  to  it  in  the 


92  MARS 

heyday  of  its  youth,  in  June,  1894,  when  it 
was  girdled  by  its  broad  blue  belt.  We  have 
seen  that  we  have  reason  to  believe  this  to  be 
in  all  probability  a  polar  sea,  a  real  body  of 
water.  There  is,  therefore,  water  on  the  sur- 
face of  Mars.  We  also  mark  that  this  body  of 
water  is  ephemeral.  It  exists  while  the  ice- 
cap is  melting,  and  then  it  somehow  vanishes. 
What  becomes  of  it,  and  whether  there  be  other 
bodies  of  water  on  the  planet,  either  permanent 
or  temporary,  we  will  now  go  on  to  inquire. 

II.  AKEOGRAPHT 

As  in  the  course  of  our  inquiry  we  shall  have 
occasion  to  refer  familiarly  to  different  Martian 
features,  we  had  best  begin  it  with  some  slight 
exposition  of  Martian  geography,  or  of  areo- 
graphy,  as  it  may  by  analogy  be  called.  To  get 
this  we  will,  by  the  help  of  Plates  III.  to  XIV., 
suppose  ourselves  to  be  viewing  the  planet 
from  some  standpoint  in  space,  and  watching  the 
surface  features  pass  in  procession  under  our 
gaze  as  the  rotation  of  the  planet  brings  them 
successively  round  into  view.  In  the  matter 
of  names  the  map  of  the  planet  toward  the  end 
of  the  book,  with  its  accompanying  index,  will 
give  identification.  We  may  thus  make  a  far 
journey  without  leaving  home,  and  from  the 
depths  of  our  arm-chairs  travel  in  spirit  to  lands 
we  have  no  hope  of  ever  reaching  in  body. 


AREOGRAPHY  93 

We  may  add  to  this  the  natural  delight  of  the 
explorer,  for  we  shall  be  gazing  upon  details  of 
Martian  geography  never  till  last  summer  seen 
by  man. 

Areography  is  a  true  geography,  as  real  as 
our  own.  Quite  unlike  the  markings  upon 
Jupiter  or  Saturn,  where  all  we  see  is  cloud, 
in  the  markings  on  Mars  we  gaze  upon  the 
actual  surface  features  of  the  Martian  globe. 
That  we  do  so  we  know  from  the  permanency 
of  the  spots  and  patches  thus  revealed  to  us. 
They  change  in  appearance,  indeed,  according 
to  times  and  seasons,  but  they  alter  as  true 
surface  features  would,  not  like  cloud-belts  that 
gather  to-day  and  vanish  forever  to-morrow. 
That  the  markings  are  essentially  permanent 
has  been  known  ever  since  Cassini  in  1666 
definitely  discovered,  what  Huyghens  had 
thought  to  detect  in  1659,  the  rotation  of  the 
planet,  by  means  of  their  periodic  presentations. 

The  twelve  views  we  shall  here  scan  are  of 
the  nature  of  a  map,  made  in  November,  1894. 
They  represent  the  ensemble  of  the  drawings 
from  this  observatory,  for  about  that  date. 
The  details  from  these  drawings  were  plotted 
upon  a  globe,  which  was  then  tilted  toward  the 
observer  at  the  angle  at  which  the  Martian 
south  pole  itself  was  tilted  toward  the  Earth 
during  November,  and  photographed  at  inter- 
vals of  30°.  The  negatives  were  then  made  to 


94  MARS 

conform  as  near  as  might  be  to  the  actual  look 
of  the  planet.  To  photograph  minute  planetary 
markings  directly  is,  for  reasons  too  long  to 
state  here,  impossible.  The  views  give  between 
them  the  whole  surface  of  the  planet  shown  us 
at  what  corresponds  to  our  first  of  August. 
Thus,  neither  the  polar  cap  nor  the  polar  sea 
appear  in  the  pictures,  for  both  had  then  dis- 
appeared. Nor  do  the  southern  parts  of  the  so- 
called  straits  show,  for  a  similar  reason.  But 
from  a  knowledge  of  the  features  here  presented 
the  reader  will  find  interpolation  of  any  others 
referred  to  easy. 

Previous  to  the  present  chart,  the  most  de- 
tailed map  of  the  planet  was  Schiaparelli's, 
made  in  1888.  On  comparison  with  his,  it  will 
be  seen  that  the  present  one  substantially  con- 
firms all  his  detail,  and  adds  to  it  about  as  much 
more.  I  have  adopted  his  nomenclature,  and 
in  the  naming  of  the  newly  found  features 
have  selected  names  conformable  to  his  scheme, 
which  commends  itself  both  on  practical  and  on 
poetic  grounds. 

We  will  begin  our  journey  at  the  origin  of 
Martian  longitudes  and  travel  west,  taking  the 
points  of  the  compass  as  they  would  appear 
were  we  standing  upon  the  planet.  As  all 
astronomical  pictures  are,  for  optical  reasons, 
upside  down,  south  lies  at  the  top  of  the  pic- 
tures, west  to  the  right,  north  at  the  bottom, 


AREOGRAPHY  95 

and  east  to  the  left.  Mars  rotates  as  the 
Earth  does,  from  west  to  east,  so  that  day  as  it 
advances  across  the  face  of  the  planet  follows 
the  order  here  shown  in  Plates  III.  to  XIV.,  the 
order  in  which  we  shall  observe  them.  Places 
on  the  right  of  the  picture  are  in  the  morning 
of  their  Martian  day ;  places  on  the  left,  in  its 
afternoon.  To  facilitate  reference  by  longitude 
and  latitude,  the  globe  has  been  belted  by 
meridians  and  parallels  each  10°  apart,  and  the 
meridians  have  been  numbered  along  the 
equator.  This  premised,  we  will  suppose  our- 
selves to  be  standing  on  the  equator  at  its  in- 
tersection with  the  0°  meridian.  (Plate  III.) 

It  will  be  noticed  that  the  0°  meridian  passes 
through  the  tip  of  a  triangular  peninsula  that 
juts  out  into  a  dark  area  curiously  forked,  half 
way  across  the  picture  and  about  two  thirds 
way  down  it.  The  tip  of  this  triangle  is  the 
received  Greenwich  of  Martian  longitudes,  and 
has  been  named  by  Schiaparelli  the  Fastigium 
Aryn,  such  having  been  the  name  of  a  mytho- 
logic  spot  supposed  by  the  ancients  to  lie  mid- 
way between  the  east  and  west,  the  north  and 
south,  the  zenith  and  nadir.  It  thus  makes  a 
fitting  name  for  the  starting-point  of  Martian 
longitudes  and  the  beginning  of  time.  The 
dark  forked  area,  called  by  Proctor  "  Dawes' 
Forked  Bay,"  is  now  commonly  called  the 
Sabaeus  Sinus.  At  the  times  these  marine 


96  MARS 

names  were  bestowed,  it  was  supposed  that  the 
dark  markings  really  represented  water.  We 
have  now  reason  to  believe  that  such  is  not  the 
case.  But  it  is  better  to  keep  the  old  names, 
although  I  shall  employ  them  in  a  Pickwickian 
sense,  much  as  we  still  speak  of  the  Seas  of 
the  Moon,  the  Mare  Tranquillitatis,  or  the  Mare 
Serenitatis,  of  which  only  the  adjectives  have  in 
them  anything  of  truth. 

To  the  west  of  the  Sabaeus  Sinus  lies  an- 
other dark,  wedge-shaped  area,  longer  than 
it  but  single  instead  of  double.  This  is  the 
Margaritifer  Sinus,  or  the  Pearl-bearing  Gulf, 
so  named  before  it  was  known  that  that  name 
possessed  any  significance.  But  a  prescience 
must  have  presided  over  its  christening.  For 
we  now  know  that  there  is  indeed  a  pearl  at 
the  bottom  of  it,  —  the  round  spot  shown  in 
the  picture. 

Two  lines  will  be  noticed  prolonging  the  twin 
forks  of  the  Sabaeus  Sinus.  If  we  let  our  look 
follow  down  them,  we  shall  mark  others  and 
then  yet  others,  and  so  we  might  proceed  from 
line  to  line  all  over  the  bright  areas  of  the 
planet.  These  lines  are  the  famous  canals  of 
Mars.  With  regard  to  their  surprising  symme- 
try, it  is  only  necessary  to  say  that  the  better 
they  are  seen  the  more  symmetrical  they  look. 
Of  the  two  first  mentioned,  the  right-hand  one 
is  the  Gihon,  the  left-hand  one  the  Hiddekel, 


MARS 
LONGITUDE  o°  ON  THE  MERIDIAN 


MARS 
LONGITUDE  30°  ON  THE  MERIDIAN 


AREOGRAPHY  97 

and  the  spot  at  the  limit  of  the  latter  is  the 
Lacus  Ismenius.  From  the  pearl  at  the  bottom 
of  the  Margaritifer  Sinus,  the  Oxia  Palus,  the 
Oxus  runs  nearly  north  to  the  Pallas  Lacus, 
while  another  canal,  the  Indus,  makes  off  north- 
west. 

Nearly  in  the  centre  of  the  disk  are  seen  two 
of  those  strange  comet-tail  peninsulas  that  con- 
stitute so  peculiar  a  feature  of  Martian  geo- 
graphy. The  lower  is  Deucalionis  Regio;  the 
upper,  Pyrrhae  Regio.  Across  them  show  two 
streaks,  which,  followed  up,  will  be  found  to 
join  other  streaks  traversing  the  dark  regions. 
These  introduce  us  to  Mr.  Douglass'  discovery 
of  a  whole  system  of  canals  in  the  dark  regions, 
paralleling  the  system  in  the  bright  areas, — 
being  similarly  straight  and  similarly  inter- 
secting one  another,  with  spots  at  the  intersec- 
tions, making  what  Mr.  Douglass  aptly  terms  a 
checkerboard  effect,  as  we  shall  see  more  strik- 
ingly when  we  get  round  to  the  other  side  of 
the  planet. 

In  Plate  IV.  the  markings  have,  under  the 
rotation  of  the  planet,  all  swung  30°  to  the  east, 
thus  bringing  others  into  view  from  the  west. 
The  great  swath  obliquely  belting  the  disk  is 
the  canal  called  the  Jamuna.  It  was,  at  the 
time  this  picture  represents  it,  apparently  in 
process  of  doubling.  Crossing  it  obliquely  is 
the  Hydraotes.  More  conspicuous  are  two  dark 


98  MARS 

swaths  that  make  with  the  Jamuna  a  nearly 
right-angled  triangle.  The  lower  one  parallel 
to  the  edge  of  the  disk  is  the  Dardanus ;  the 
other,  ending  at  the  south  with  the  Jamuna  in 
the  Aurorae  Sinus,  is  the  Ganges,  one  of  the 
largest  and  most  important  of  the  Martian 
canals.  At  the  date  of  the  drawing,  it  was  dis- 
tinctly double.  The  doubling  is  very  curiously 
prolonged  by  a  narrow  rectangle  lying  in  the 
midst  of  the  dark  regions  to  the  south.  Some 
idea  of  the  size  of  these  strangely  geometrical 
markings  may  be  got  by  remembering  that  a 
degree  on  Mars  represents  thirty-seven  miles. 
Skirting  the  edge  of  the  dark  regions  westward, 
we  come  to  a  short  canal,  the  Hebe,  leading  to 
the  Fons  Juventae,  one  of  the  tiniest  markings 
perceptible  on  the  disk,  from  which,  however, 
some  six  canals  have  been  found  to  radiate. 
Schiaparelli  detected  it  in  1877,  searched  for 
it  in  vain  in  1879,  but  at  subsequent  oppositions 
found  it  again,  happier  than  Ponce  de  Leon  in 
his  futile  quest  after  an  earthly  Fountain  of 
Youth.  Proceeding  still  farther  west,  we  reach 
the  entrance  to  the  Agathodaemon,  at  the  point 
where  the  edge  of  the  dark  regions  abruptly 
trends  southward.  This  canal  brings  us  to  the 
Solis  Lacus  region,  one  of  the  most  interesting 
parts  of  the  planet. 

In  Plate  V.  it   has   swung  round  into  bet- 
ter view,  where  we  will  therefore  consider  it. 


MARS 
LONGITUDE  60°  ON  THE  MERIDIAN 


AREOGRAPHY  99 

The  Soils  Lacus  is  a  great  oval  patch,  measur- 
ing along  its  longest  diameter  five  hundred  and 
forty  miles.  With  small  telescopic  power  or  in 
poor  air  it  appears  of  uniform  tint  through- 
out, but  under  better  visual  conditions  dark 
spots  appear  in  it,  and  bright  causeways,  which 
divide  it  into  five  portions.  Its  longitudinal 
dividing  line  is  prolonged  into  the  Nectar,  the 
short  canal  connecting  it  with  the  dark  regions 
to  the  east.  The  Nectar  thus  appears  double. 
Nor  does  the  causeway  stop  here.  It  continues 
on  between  double  dark  lines  until  it  reaches 
the  long  rectangular  area  spoken  of  before  as  a 
sort  of  continuation  of  the  Ganges. 

But  a  second  feature  of  this  region  is  no  less 
noteworthy.  Surrounding  the  Solis  Lacus  is  a 
perfect  cordon  of  canals  and  spots,  the  chief  of 
which  are  the  Tithonius  Lacus,  nearly  due  north, 
and  the  Lacus  Phoenicis,  or  Phoenix  Lake,  north- 
west. The  spots  are  strung  like  beads  upon 
the  loop  of  the  Agathodaemon  and  the  Dae- 
mon. From  the  northeast  end.  of  this  string  of 
spots  runs  the  Chrysorrhoas  to  the  Lacus  Lunae 
on  the  fifty-eighth  meridian.  Below  it  is  the 
Labeatis  Lacus,  from  which  the  Gigas  starts 
west,  to  be  lost  in  the  limb-light. 

In  the  next  plate  (Plate  VI.),  the  Solis  Lacus 
is  central,  the  Lacus  Phoenicis  somewhat  to  the 
right  of  the  centre ;  and  southwest  of  the  Lacus 
Phoenicis  is  the  Beak  of  the  Sirens,  the  eastern 


100  MARS 

end  of  the  sea  of  the  same  name,  which  has  just 
come  round  the  corner  of  the  disk.  The  canal 
connecting  it  with  the  Phoenix  Lake  is  the 
Araxes ;  and  at  various  angles  to  this,  like 
spokes  of  a  wheel  about  the  Phoenix  Lake  for 
hub,  are  many  more  canals,  the  one  lying  most 
nearly  due  south  being  the  Phasis.  Connecting 
with  this  network  of  canals  is  a  similar  network 
of  streaks  in  the  dark  regions,  making  a  set  of 
triangles,  from  which  still  other  canals  run  up 
almost  straight  toward  the  south  pole. 

Between  the  dark  regions  and  the  Beak  of 
the  Sirens  is  the  peninsula  Phaetontis,  crossing 
which  some  way  up  is  a  short  canal  known  as 
Herculis  Columnae.  Due  north  of  the  Lacus 
Phoenicis  is  the  spot  Ceraunius,  joined  to  the 
Lacus  Phoenicis  by  the  Iris,  and  to  the  Titho- 
nius  Lacus  by  the  Fortunae.  It  is  also  crossed 
by  the  Gigas,  the  very  long  canal  in  the  right- 
hand  lower  part  of  the  disk,  of  which  we  saw 
the  beginning  in  the  last  plate,  and  shall  not 
see  the  end  till  we  reach  the  next  one. 

Westward  of  the  Lacus  Phoenicis  there  be- 
gins to  show  a  congeries  of  spots  and  connecting 
canals,  which  come  out  still  more  strikingly  in 
Plate  VII.  The  great  canal  beaded  with  spots, 
which  in  the  picture  traverses  nearly  the  centre 
of  the  disk,  is  the  Eumenides,  and  its  continua- 
tion, the  Orcus.  Its  farther  end  is  lost  in  the 
limb-light.  At  an  angle  to  it,  running  nearly 


MARS 
LONGITUDE  90°  ON  THE  MERIDIAN 


PLATE  VII 


MARS 
LONGITUDE  120°  ON  THE  MERIDIAN 


AREOGRAPHY  101 

northwest  from  the  Lacus  Phoenicis,  is  the  Pyri- 
phlegethon.  In  this  plate  the  Sea  of  the  Sirens 
is  well  on,  its  beak  being  almost  on  the  central 
meridian.  From  its  north  coast  strike  down 
a  great  many  canals,  all  going  as  far  as  the 
Eumenides  and  some  continuing  past  it.  The 
first  one  from  the  Beak  of  the  Sirens  is  the 
Sirenius.  It  crosses  the  Eumenides  at  the  first 
of  its  large  spots  after  leaving  the  Phoenix  Lake, 
the  Lucus  Arsine.  To  the  next  spot,  known 
as  the  Nodus  Gordii,  the  Gorgon  comes  down 
from  the  centre  of  the  coast-line,  meeting  the 
Gigas,  which  itself  debouches,  at  the  west  end 
of  the  sea,  into  what  is  called  the  Sinus  Titanum, 
or  Gulf  of  the  Titans. 

In  Plate  VIII.  the  Sinus  Titanum  has  come 
round  into  view.  Owing  to  its  conspicuousness 
at  certain  seasons,  it  is  one  of  the  most  impor- 
tant features  on  the  planet  to  us,  and  seems  to 
be  to  .the  planet  itself,  as  some  seven  canals 
radiate  from  it.  These  are  the  Gigas,  previ- 
ously described,  and  to  the  right,  in  the  order 
here  enumerated,  the  Steropes,  the  Brontes,  the 
Titan,  —  the  one  straight  down  the  disk,  —  the 
Arges,  the  Gyes,  and  the  Tartarus;  the  last 
traveling  to  the  Trivium  Charontis  invisible 
in  this  plate.  Of  the  separate  existence  of  the 
Arges  and  the  Gyes  I  am  not  quite  certain. 
These  great  canals  show  like  the  sticks  of  a  fan, 
with  the  Sinus  itself  for  pivot. 


102  MARS 

The  Sea  of  the  Sirens  is  now  nearly  central. 
To  the  west,  dividing  it  from  the  Mare  Cimme- 
rium,  which  is  just  coming  into  view,  is  the 
peninsula  Atlantis,  curiously  uniting  the  conti- 
nents to  the  islands  to  the  south.  Belting  the 
disk  from  east  to  west  is  the  Eumenides-Orcus, 
strung  with  spots. 

Parallel  to  the  Eumenides-Orcus,  and  skirt- 
ing the  north  shore  of  the  Sea  of  the  Sirens,  is 
the  Erynnis.  Half  way  between  this  and  the 
Eumenides  is  another  parallel  canal,  the  Parcae. 
Curving  round  the  bottom  of  the  disk  is  a  chain 
of  canals,  the  Pyriphlegethon,  Acheron,  and 
Erebus,  the  last  of  which  runs  to  the  Trivium 
Charontis.  At  the  junctions  of  these  various 
canals  may  be  seen  any  number  of  spots. 

On  the  next  plate  (Plate  IX.)  the  Trivium 
Charontis  itself  has  come  into  view  toward  the 
lower  right-hand  part  of  the  disk.  Two  nearly 
parallel  canals,  a  double  Hades,  join  it  to  the  Pro- 
pontis,  the  spot  almost  at  the  limb.  The  Titan 
shows  well  near  the  centre  of  the  disk.  Were 
the  centre  ten  degrees  farther  east,  the  canal 
would  appear  more  striking  yet.  For  so  straight 
is  it,  and  so  nearly  due  north  and  south  does  it 
lie,  that  when  it  comes  to  the  meridian  it  seems 
that  meridian  itself.  On  this  plate  we  have  the 
western  end  of  the  Eumenides-Orcus,  at  whose 
eastern  end  we  began  several  plates  back  when 
we  left  the  Phoenix  Lake.  This  will  give  some 


PLATE  VIII 


MARS 
LONGITUDE  150°  ON  THE  MERIDIAN 


*..  •*  .  ~  •--.* 


MARS 

LONGITUDE  180°  ON  THE  MERIDIAN 


AREOGRAPHY  103 

idea  of  the  immense  length  of  the  canal,  which 
is  no  less  than  three  thousand  four  hundred  and 
fifty  miles  long.  Nearly  in  the  centre  of  the 
disk  is  the  peninsula  Atlantis,  the  most  easterly 
of  the  set  of  comet- tail  peninsulas  similar  to 
those  seen  in  Plate  I.,  all  connecting  the  so- 
called  continent  with  the  islands  to  the  south. 
These  islands  look  not  unlike  great  vertebrae 
of  the  planet's  backbone,  in  consequence  of  the 
canals  which  cut  them  up  so  symmetrically. 
Atlantis  shows  well,  between  Mare  Sirenum  and 
Mare  Cimmerium,  two  areas  suggestively  alike 
in  general  shape  and  directional  trend.  Both 
are  seen  to  be  crossed  by  canals  which  connect, 
at  what  resemble  nicks  in  the  coast-line,  with 
the  canals  in  the  bright  regions. 

In  Plate  X.  the  Mare  Cimmerium  is  cen- 
tral. So,  also,  well  down  the  disk,  is  the  Tri- 
vium  Charontis.  This  is  a  very  important 
junction,  no  less  than  nine  canals  already  being 
known  to  connect  with  it,  which,  taken  in  the 
order,  east,  north,  west,  and  south,  are  the 
Orcus,  the  Erebus,  the  twin  Hades,  the  Styx, 
the  Cambyses,  the  Cerberus,  the  Laestrygon, 
the  Tartarus,  and  so  back  to  the  Orcus  again. 
In  this  picture  the  Laestrygon  traverses  nearly 
the  centre  of  the  disk.  To  the  right  of  the 
Trivium  Charontis  is  the  region  called  Elysium, 
one  of  the  brightest  parts  of  the  planet.  It 
was  here  that  Mr.  Douglass  made  his  interest- 


104  MARS 

ing  observation,  last  September,  of  a  remarkable 
change  of  tint  from  bright  to  sombre,  and  back 
to  bright  again,  in  the  course  of  forty-eight 
hours ;  suggesting  perhaps  the  formation  and 
dissipation  of  cloud,  perhaps  the  deposition  and 
subsequent  melting  of  hoar-frost  over  an  area 
of  some  hundreds  of  square  miles. 

Returning  to  the  Mare  Cimmerium,  we  ob- 
serve in  the  middle  of  it  a  long,  lighter  streak, 
Cimmeria,  scarcely  perceptible  at  this  last  oppo- 
sition, and,  barring  its  western  end,  the  second 
in  the  procession  of  similarly  inclined  peninsulas 
that  follow  one  another  westward  upon  this  side 
of  the  planet,  the  peninsula  Hesperia,  a  place 
with  a  history,  as  will  appear  later  on. 

In  the  next  picture  (Plate.  XI)  Hesperia  is 
central,  dividing  the  Mare  Cimmerium  on  the 
left  from  the  Mare  Tyrrhenum  on  the  right. 
The  lower  end  of  the  latter  is  called  the  Syrtis 
Minor,  in  contradistinction  to  the  Syrtis  Major, 
which  is  just  appearing  round  the  western  limb. 
From  the  bay,  so  to  speak,  upon  the  left  of 
Hesperia,  two  canals  proceed  down  the  disk  in 
divergent  directions,  —  the  most  easterly  one 
the  Aethiops,  the  other  the  Achelous.  From 
the  Syrtis  Minor  proceed  two  others,  more  or 
less  similarly  inclined,  —  the  Lethes  and  the 
Amenthes. 

To  the  west  of  Hesperia  and  parallel  to  it  is 
a  third  comet-tail  peninsula,  Lemuria,  connect- 


MARS 

LONGITUDE   210°  ON   THE   MERIDIAN 


MARS 
LONGITUDE  240°  ON  THE  MERIDIAN 


PLATE  XII 


MARS 
LONGITUDE  270°  ON  THE  MERIDIAN 


AREOGRAPHY  105 

ing  Ausonia  at  the  south  with  Libya  to  the 
north,  Libya  being  upon  the  equator.  This 
region  (Plate  XII.)  is  interesting  as  having  been 
the  scene  of  great  changes  at  previous  oppo- 
sitions. There  used  to  be  a  spot,  the  Lake 
Moeris,  in  the  midst  of  it,  joined  by  the  Nepen- 
thes—  the  canal  running  east  and  west  about 
eight  degrees  north  of  the  equator  —  to  the 
Syrtis  Major,  the  great  dark  gulf  somewhat  to 
the  west  of  the  central  meridian  in  the  picture. 
Latterly  the  Syrtis  Major  seems  to  have  en- 
croached upon  Libya,  and,  at  the  last  opposi- 
tion, only  the  faintest  glimpses  could  be  got  of 
Lake  Moeris,  which  showed  chiefly  as  a  bay  of 
the  Syrtis  Major  itself.  Here,  as  elsewhere,  I 
use  aquatic  names  with  terrestrial  understand- 
ing- 
Parallel  in  a  general  way  to  the  Nepenthes, 
and  about  as  much  below  it  as  it  is  below  the 
coast-line,  lies  the  Astapus,  which  joins  the  bot- 
tom of  the  Syrtis  Major  to  the  ends  of  the 
Amenthes,  Lethes,  and  Achelous. 

In  Plate  XIII.  two  features  are  striking,  both 
not  far  from  central  on  the  disk,  —  the  lower, 
the  Syrtis  Major;  the  upper,  Hellas.  The 
Syrtis  Major  was  the  first  marking  to  be  cer- 
tainly recognized  on  Mars.  It  appears  in  a 
drawing  by  Huyghens  made  on  October  13, 
1659,  the  first  drawing  of  Mars  worthy  the 
name  ever  made  by  man,  and  reproduced  on 


106  MARS 

page  20  from  Flammarion's  "  La  Planete  Mars." 
It  is  thus  our  oldest  Martian  acquaintance. 
Hellas  is  the  surprisingly  round,  bright  area 
nearly  on  the  meridian,  and  nearly  half  way 
from  the  equator  to  the  south  pole.  It  is  very 
strangely  quartered  by  two  canals,  the  Alpheus, 
dividing  it  almost  due  north  and  south;  and  the 
Peneus,  cutting  it  almost  due  east  and  west. 
Between  it  and  the  Syrtis  Major  is  the  Mare 
Hadriaticum,  a  blue-green  area  intersected  by 
bright  causeways  and  seamed  by  dark  canals. 

In  the  lower  right-hand  portion  of  the  disk  is 
an  important  region,  bounded  on  the  east  by 
the  Syrtis  Major,  on  the  north  by  the  Nilosyrtis 
and  the  Protonilus,  on  the  west  by  the  Hidde- 
kel,  and  on  the  south  by  the  long  dark  area 
to  the  north  of  Deucalionis  Regio.  Its  south- 
eastern cape  is  the  Hammonis  Cornu ;  its'  south- 
western one,  which  appears  in  Plate  XIV.,  is 
the  Edom  promontory.  It  is  a  region  prolific 
in  double  canals.  The  two  most  important  of 
these  are  the  Phison  and  the  Euphrates.  Both 
start  from  the  centre  of  the  coast  of  the  long 
dark  area  between  the  Deucalionis  Regio  and 
the  continent,  and  run,  the  Phison  northeast  to 
the  western  end  of  the  Nilosyrtis,  in  longitude 
300°,  latitude  33°  north ;  the  Euphrates,  nearly 
due  north  to  the  Lacus  Ismenius,  longitude 
337°,  latitude  37°  north,  where  it  connects  with 
the  Hiddekel.  Parallel  to  the  coast-line  and 


PLATE  XIII 


•: 


MARS 

LONGITUDE  300°  ON  THE  MERIDIAN 


PLATE  XIV 


**•'  .^-' 


m 


MARS 
LONGITUDE  330°  ON  THE  MERIDIAN 


SEAS  107 

about  15°  to  the  north  of  it  is,  on  the  east,  the 
Typhon,  shown  double ;  on  the  west  the  Orontes, 
still  single.  Two  other  doubles  shown  in  the 
picture  I  saw  also  in  this  region,  though  I  am 
not  yet  certain  that  they  are  distinct  from  the 
Phison  and  the  Euphrates,  as  the  four  were  not 
seen  together.  I  have  introduced  them  in  the 
place  where  I  saw  them,  because,  first,  no  op- 
tical effect  explains  any  such  shift ;  and,  second, 
they  run  through  and  to  well-seen  spots,  which 
renders  it  more  likely  that  they  are  distinct 
canals. 

Between  the  Euphrates  and  the  Sabaeus 
Sinus  are  several  canals  and  spots  that  show 
the  minute  manner  in  which  the  Martian  sur- 
face is  cut  up.  But  so  much  only  hints  at  the 
state  of  things  existent  there.  From  the  mark- 
ings, not  well  enough  seen  to  admit  of  mapping, 
it  is  apparent  that  the  system  of  lines  and  spots 
is  very  complete  all  over  the  planet. 

This  brings  us  back  again  to  the  Sabaeus 
Sinus  and  the  Fastigium  Aryn,  from  which  we 
set  out,  after  a  journey  which  it  takes  the  ro- 
tation of  the  planet  twenty-four  hours  thirty- 
seven  minutes  and  about  twenty-three  seconds 
to  accomplish. 

III.    SEAS. 

While  it  existed  in  any  size,  the  polar  sea 
was  bordered  on  the  north,  all  the  way  round 


108  MARS 

and  during  all  the  time  it  was  visible,  by  blue- 
green  areas.  These  blue-green  areas  were 
strewn  with  several  more  or  less  bright  regions, 
while  below  them  came  the  great  reddish-ochre 
stretches  of  the  disk.  Now,  the  blue-green 
areas  have  generally  been  considered  to  be  seas, 
just  as  the  reddish-ochre  regions  have  been 
held  to  be  land.  That  the  latter  are  land  there 
is  very  little  doubt ;  not  only  land,  but  nothing 
but  land,  —  land  very  pure  and  simple ;  that  is, 
deserts.  For  they  behave  just  as  deserts  should 
behave,  that  is,  by  not  behaving  at  all;  re- 
maining, except  for  certain  phenomena  to  be 
specified  later,  unchangeable. 

With  the  so-called  seas,  however,  the  case  is 
different.  Several  important  facts  conspire  to 
throw  grave  doubt,  and  worse,  upon  their 
aquatic  character.  To  begin  with,  they  are  of 
every  grade  of  tint,  —  a  very  curious  feature 
for  seas  to  exhibit,  unless  they  were  every- 
where but  a  few  feet  deep ;  which  again  is  a 
most  singular  characteristic  for  seas  that  cover 
hundreds  of  thousands  of  square  miles  in  ex- 
tent, —  seas,  that  is,  as  big  as  the  Bay  of  Ben- 
gal. The  Martian  surface  would  have  to  be 
amazingly  flat  for  this  to  be  possible.  We 
know  it  to  be  relatively  flat,  but  to  be  as  flat  as 
all  this  would  seem  to  pass  the  bounds  of  credi- 
ble simplicity.  Here  also  Professor  W.  H.  Pick- 
ering's polariscope  investigations  come  in  with 


SEAS  109 

effect,  for  he  found  the  light  from  the  supposed 
seas  to  show  no  trace  of  polarization.  Hence 
these  were  probably  not  water. 

In  parenthesis  we  may  here  take  notice  of 
the  absence  of  a  certain  phenomenon  whose 
presence,  apparently,  should  follow  upon  water 
surfaces  such  as  the  so-called  seas  would  offer 
us.  Although  its  absence  is  not  perhaps  defini- 
tive as  to  their  marine  character,  it  is  certainly 
curious,  and  worth  noting.  If  a  planet  were 
covered  by  a  sheet  of  water,  that  water  surface 
would,  mirror-like,  reflect  the  sun  in  one  more 
or  less  definite  spot.  Looked  at  from  a  dis- 
tance, this  spot  would,  were  it  bright  enough, 
be  seen  as  a  high  light  on  the  dark  background 
of  the  ocean  about  it.  It  would  seem  to  be  a 
fixed  star  at  a  certain  point  on  the  disk,  the 
surface  features  rotating  under  it.  The  neces- 
sary position  is  easily  calculated,  and  this  shows 
that  parts  of  the  so-called  seas,  especially  at 
oppositions  like  the  last  one,  pass  under  the 
point.  There  remains  merely  the  question  of 
sufficient  brilliancy  in  the  spot  for  visibility; 
but  as  in  the  case  of  Mars  its  brilliancy  should 
be  equal  to  that  of  a  star  of  the  first  magni- 
tude, it  would  seem  brilliant  enough  to  be  seen. 
No  such  starlike  effect  in  such  position  has  ever 
been  noticed  coming  from  the  blue-green  re- 
gions. From  this  bit  of  negative  evidence,  to 
be  taken  for  what  it  is  worth,  we  return  again 
to  what  there  is  of  a  positive  sort. 


110  MARS 


Tot  only  do  different  parts  of  the  so-called 
seas  contrast  in  tint  with  one  another,  but  the 
same  part  of  the  same  sea  varies  in  tint  at  dif- 
ferent times.  Schiaparelli  noticed  that,  at  suc- 
cessive oppositions,  the  same  sea  showed  differ- 
ent degrees  of  darkness,  and  he  suggested  that 
the  change  in  tone  was  dependent  in  some  way 
upon  the  Martian  seasons. 

Observations  at  Flagstaff  have  demonstrated 
this  to  be  the  case,  for  it  has  been  possible  to 
see  the  tints  occur  consecutively.  In  conse- 
quence, we  know  not  only  that  changes  take 
place  on  the  surface  of  Mars  other  than  in  the 
polar  cap,  and  very  conspicuous  ones  too,  but 
that  these  are  due  to  the  changing  seasons  of 
the  planet's  year.  We  will  now  see  what  they 
look  like. 

To  the  transubstantiation  of  changes  of  the 
sort  it  is  a  prime  essential  that  the  drawings 
from  whose  comparison  the  contrast  appears 
should  all  have  been  made  by  the  same  person, 
at  the  same  telescope,  under  as  nearly  as  possi- 
ble the  same  atmospheric  conditions,  since  other- 
wise the  personal  equation  of  the  observer,  the 
impersonal  inequalities  of  instruments,  and  the 
special  atmosphere  of  the  station  play  so  large 
a  part  in  the  result  as  to  mask  that  other  factor 
in  the  case,  any  change  in  the  planet  itself. 
How  easily  this  masking  is  accomplished  ap- 
pears from  drawings  made  by  different  ob- 


PLATE  XV 


FIG.  I.     Syrtis  Major  at  June  presentation 
Long.  290°.     Lat.  centre  of  disk  24°  South 


FIG.  II.     Syrtis  Major  at  October  presentation 
Long.  305°.    Lat.  centre  of  disk  20°  South 

SYRTIS   MAJOR 

SHOWING  SEASONAL  CHANGE  DURING  1894 


SEAS  111 

servers  of  the  same  Martian  features  at  substan- 
tially the  same  moment.  Several  interesting 
specimens  of  such  personal  peculiarities  may  be 
seen  by  the  curious  in  Flammarion's  admirable 
thesaurus,  "  La  Planete  Mars."  In  some  of  these 
likenesses  of  the  planet  it  is  pretty  certain  that 
Mars  would  never  recognize  himself. 

To  have  drawings  simply  swear  at  one  an- 
other across  a  page  is,  in  the  interests  of  de- 
duction, objectionable.  For  their  testimony  to 
be  worth  having,  they  must  agree  to  differ. 
If,  therefore,  Mars  is  to  be  many,  his  draughts- 
man must  be  one.  So  much,  at  least,  is  fulfilled 
by  the  drawings  in  which  the  changes  now  to  be 
described  are  recorded ;  for  they  were  all  made 
by  me,  at  the  same  instrument-  under  the  same 
general  atmospheric  conditions.  As  the  same 
personality  enters  all  of  them,  it  stands,  as  be- 
tween them,  eliminated  from  all,  to  increased 
certainty  of  deduction.  Since,  furthermore, 
the  drawings  were  all  made  in  the  months 
preceding  and  following  one  opposition,  change 
due  to  secular  variation  is  reduced  to  a  mini- 
mum. As  a  matter  of  fact,  the  changes  are 
such  as  to  betray  their  own  seasonal  character. 
They  constitute  a  kinematical  as  opposed  to  a 
statical  study  of  the  planet's  surface. 

The  changes  are  much  more  evident  than 
might  be  supposed.  Indeed,  they  are  quite  un- 
mistakable. As  for  their  importance,  it  need 


112  MARS 

only  be  said  that  deduction  from  them  furnishes, 
in  the  first  place,  inference  that  Mars  is  a  living 
world,  subject  to  an  annual  cycle  of  surface 
growth,  activity,  and  decay ;  and  shows,  in  the 
second  place,  that  this  Martian  yearly  round  of 
life  must  differ  in  certain  interesting  particulars 
from  that  which  forms  our  terrestrial  expe- 
rience. The  phenomena  evidently  make  part 
of  a  definite  chain  of  changes  of  annual  devel- 
opment. So  consecutive,  and,  in  their  broad 
characteristics,  apparently  so  regular,  are  these 
changes,  that  I  have  been  able  to  find  corrobora- 
tion  of  what  appears  to  be  their  general  scheme 
in  drawings  made  at  a  previous  opposition.  In 
consequence,  I  believe  it  will  be  possible  in  future 
to  foretell,  with  something  approaching  the  cer- 
tainty of  our  esteemed  weather  bureau's  prog- 
nostications, not  indeed  what  the  weather  will 
be  on  Mars,  —  for,  as  we  have  seen,  it  is  more 
than  doubtful  whether  Mars  has  what  we  call 
weather  to  prognosticate,  —  but  the  aspect  of 
any  part  of  the  planet  at  any  given  time. 

The  changes  in  appearance  now  to  be  chroni- 
cled refer,  not  to  the  melting  of  the  polar 
snows,  except  as  such  melting  forms  the  neces- 
sary preliminary  to  what  follows,  but  to  the 
subsequent  changes  in  look  of  the  surface  itself. 
To  their  exposition,  however,  the  polar  phe- 
nomena become  inseparable  adjuncts,  since  they 
are  inevitable  ancillaries  to  the  result. 


SEAS  113 

With  the  familiar  melting  of  the  snow-cap 
begins  the  yearly  round  of  the  planet's  life. 
With  the  melting  of  our  own  arctic  or  antarctic 
cap  might  similarly  be  said  to  begin  the  earth's 
annual  activity.  But  here  at  the  very  outset 
there  appears  to  be  one  important  difference  be- 
tween the  two  planets.  On  the  earth  the  rela- 
tion of  the  melting  of  the  polar  snows  to  the 
awakening  of  surface  activity  is  a  case  of  post 
hoc  simply ;  on  Mars  it  seems  to  be  a  case  of 
propter  hoc  as  well.  For,  unlike  the  earth, 
which  has  water  to  spare,  and  to  which,  there- 
fore, the  unlocking  of  its  polar  snows  is  a  matter 
of  no  direct  economic  value,  Mars  is  apparently 
in  straits  for  the  article,  and  has  to  draw  on  its 
polar  reservoir  for  its  annual  supply.  Upon 
the  melting  of  its  polar  cap,  and  the  transfer- 
ence of  the  water  thus  annually  set  free  to  go 
its  rounds,  seem  to  depend  all  the  seasonal  phe- 
nomena on  the  surface  of  the  planet. 

The  observations  upon  which  this  deduction 
is  based  extend  over  a  period  of  nearly  six 
months,  from  the  last  day  of  May  to  the  22d  of 
November.  They  cover  the  regions  from  the 
south  pole  to  about  latitude  forty  north.  That 
changes  analogous  to  those  recorded,  differing, 
however,  in  details,  occur  six  Martian  months 
later  in  the  planet's  northern  hemisphere,  is 
proved  by  what  Schiaparelli  has  seen ;  for 
though  the  general  system  is,  curiously,  one  for 


114  MARS 

the  whole  planet,  the  particular  character  of 
different  parts  of  the  surface  alters  the  action 
there  to  some  extent. 

For  an  appreciation  of  the  meaning  of  the 
changes,  it  is  to  be  borne  in  mind  through- 
out that  the  vernal  equinox  of  Mars'  southern 
hemisphere  occurred  on  April  7,  1894;  the 
summer  solstice  of  the  same  hemisphere  on 
August  31 ;  and  its  autumnal  equinox  on  Feb- 
ruary 7, 1895. 

On  the  31st  of  May,  therefore,  it  was  toward 
the  end  of  April  on  Mars.  The  south  polar  cap 
was,  as  we  have  seen,  very  large,  and  the  polar 
sea  in  proportion.  That  the  polar  sea  was  the 
darkest  and  the  bluest  marking  on  the  disk  im- 
plies that  it  was,  at  least,  the  deepest  body  of 
water  on  the  planet,  whether  the  so-called  seas 
were  seas  or  not.  But  from  the  fact  that  it  was 
quite  wide,  —  350  miles,  —  and  that  it  all  event- 
ually vanished,  it  can  hardly  have  been  very 
deep.  Its  relative  appearance,  therefore,  casts 
a  first  doubt  upon  the  fact  that  the  others  were 
seas  at  all.  This  polar  sea  plays  deus  ex  ma- 
china  to  all  that  follows. 

So  soon  as  the  melting  of  the  snow  was  well 
under  way,  long  straits,  of  deeper  tint  than 
their  surroundings,  made  their  appearance  in 
the  midst  of  the  dark  areas.  I  did  not  see  them 
come,  but  as  I  afterward  saw  them  go  it  is 
evident  that  they  must  have  come.  They  were 


SEAS  115 

already  there  on  the  last  day  of  May.  The 
most  conspicuous  of  them  lay  between  Noachis 
and  Hellas,  in  the  Mare  Australe.  It  began  in 
the  great  polar  bay,  and  thence  traversed  the 
Mare  Erythrseurn  to  the  Hourglass  Sea  (Syr- 
tis  Major).  The  next  most  conspicuous  one 
started  in  the  other  bay,  and  came  down  be- 
tween Hellas  and  Ausonia.  Although  these 
straits  were  distinguishably  darker  than  the 
seas  through  which  they  passed,  the  seas  them- 
selves were  then  at  their  darkest.  The  fact 
that  these  straits  traversed  the  seas  suffices  to 
raise  a  second  doubt  as  to  the  genuineness  of 
seas ;  the  first  suspicion  as  to  their  character  — 
coming  from  their  being  a  little  off  color ;  not  so 
blue,  that  is,  as  what  we  practically  know  to  be 
water,  the  polar  sea  —  finding  thus  corrobora- 
tion.  It  will  appear  later  that  in  all  probability 
the  straits  themselves  were  impostors,  and  that 
neither  seas  nor  straits  were  water. 

The  appearance  of  things  at  this  initial  stage 
of  the  Martian  Nile-like  inundation  last  June 
was  most  destructive  to  modern  maps  of  Mars, 
for  all  the  markings  between  the  south  polar 
cap  and  the  continental  coast-line  seemed  with 
one  consent  to  have,  as  nearly  as  might  be,  ob- 
literated themselves. 

It  was  impossible  to  fix  any  definite  boun- 
daries to  the  south  temperate  chain  of  islands, 
so  indistinguishably  did  the  light  areas  and  the 


116  MARS 

dark  ones  merge  into  each  other.  What  was 
still  more  striking,  the  curious  peninsulas  which 
connect.'  the  continent  with  the  chain  of  islands 
to  the  south  of  it,  and  form  so  singular  a  fea- 
ture of  the  planet's  geography,  were  invisible. 
One  continuous  belt  of  blue-green  stretched 
from  the  Syrtis  Major  to  the  Columns  of  Her- 
cules. 

For  some  time  the  dark  areas  continued 
largely  unchanged  in  appearance ;  that  is,  dur- 
ing the  earlier  and  most  extensive  melting  .of 
the  snow-cap.  After  this  their  history  became 
one  long  chronicle  of  fading  out.  Their  lighter 
parts  grew  lighter,  and  their  darker  ones  less 
dark.  For,  to  start  with,  they  were  made  up 
of  many  tints ;  various  shades  of  blue-green 
interspersed  with  glints  of  orange-yellow.  The 
gulfs  and  bays  bordering  the  continental  coast 
were  the  darkest  of  these  markings;  the  long 
straits  between  the  polar  sea  and  the  Syrtis 
Major  were  the  next  deepest  in  tone. 

The  first  marked  sign  of  change  was  the  re- 
appearance of  Hesperia.  Whereas  in  June  it 
had  been  practically  non-existent,  by  August  it 
had  become  perfectly  visible  and  in  the  place 
where  it  is  usually  depicted.  In  connection 
with  its  reappearance  two  points  are  to  be 
noted:  first,  the  amount  of  the  change,  for 
Hesperia  is  a  stretch  of  land  over  two  hundred 
miles  broad  by  six  hundred  miles  long;  and, 


SEAS  117 

secondly,  the  fact  that  its  previous  invisibility 
was  not  due  to  any  sort  of  obscuration.  The 
persistent  clear-cut  character  of  the  neighbor- 
ing coast-line  during  the  whole  transformation 
showed  that  nothing  of  the  nature  of  mist  or 
cloud  had  at  any  time  hidden  the  peninsula 
from  view.  A  something  was  actually  there 
in  August  which  had  not  been  there  in  June. 

As  yet  nothing  could  be  seen  of  Atlantis.  It 
was  not  until  the  30th  of  October  that  I  caught 
sight  of  it.  About  the  same  time,  the  straits 
between  the  islands,  Xanthus,  Scamandei*,  Psy- 
chrus,  and  Simois,  came  out  saliently  dark, 
a  darkness  due  to  contrast.  The  line  of  south 
temperate  islands,  with  their  separate  identity, 
was  then  for  the  first  time  apparent. 

Meanwhile  the  history  of  Hesperia  continued 
to  be  instructive.  From  having  been  absent  in 
June  and  conspicuous  in  August,  it  returned  in 
October  to  a  mid-position  of  visibility.  Vacil- 
lating as  these  fluctuations  in  appearance  may 
seem  at  first  sight,  they  were  really  quite  con- 
sistent ;  for  they  were  probably  due  to  progres- 
sive change  in  the  one  direction,  a  change  that 
was  manifested  first  in  Hesperia  itself,  and  then 
in  the  regions  round  about  it.  From  June 
to  August,  Hesperia  changed  from  a  previous 
blue-green,  indistinguishable  from  its  surround- 
ings, to  yellow,  the  parts  adjacent  remaining 
much  as  before,  As  a  consequence,  the  pe- 


118  MARS 

ninsula  stood  out  in  marked  contrast  to  the 
still  deep  blue:green  regions  by  its  side.  Later 
the  surroundings  themselves  faded,  and  their 
bleaching  had  the  effect  of  once  more  partially 
obliterating  Hesperia. 

While  Hesperia  was  thus  getting  itself  no- 
ticed, the  rest  of  the  south  temperate  zone,  as 
we  may  call  it  for  identification's  sake,  was  un- 
obtrusively pursuing  the  same  course.  Whereas 
in  June  all  that  part  of  the  disk  comprising  the 
two  Thyle,  Argyre  II.,  and  like  latitudes  was 
chiefly  blue-green,  by  October  it  had  become 
chiefly  yellow.  Still  further  south,  what  had 
been  first  white,  then  blue,  then  brown,  turned 
ochre. 

Certain  smaller  details  of  the  change  that 
came  over  the  face  of  the  dark  regions  at  the 
time  were  as  curious  as  they  were  marked.  For 
example,  the  Fastigium  Aryn,  the  tip  of  the  tri- 
angular cape  which,  by  jutting  out  from  the 
continent,  forms  the  forked  bay  called  the  Sa- 
baeus  Sinus,  and  which,  because  of  its  easy 
identification,  has  been  selected  for  the  zero 
meridian  of  Martian  longitudes,  began  in  Oc- 
tober to  undergo  strange  metamorphosis.  On 
October  15  it  shot  out  a  sort  of  tail  southward. 
On  the  16th  this  tail  could  be  followed  all  the 
way  to  Deucalionis  Regio,  to  which  it  made  a 
bridge  across  from  the  continent,  thus  cutting 
the  Sabaeus  Sinus  completely  in  two.  After  it 


PLATE  XVII 


f 


FIG.  I.    Sea  of  the  Sirens  at  June  presentation 
Long.  141°.     Lat.  centre  of  disk  24°  South 

FIG.  II.    Sea  of  the  Sirens  at  November  presentation 
Long.  156°.    Lat.  centre  of  disk  22°  South 

SEA   OF  THE   SIRENS   AND  ATLANTIS 
AT  THE  OPPOSITION  OF   1894 

SHOWING  SEASONAL  CHANGE 


SEAS  119 

had  thus  appeared,  it  continued  visible  up  to 
the  close  of  the  observations  sufficiently  detailed 
to  show  it. 

Another  curious  causeway  of  the  same  sort 
made  its  appearance  in  November,  connecting 
the  promontory  known  as  Hammonis  Cornu 
with  Hellas.  Both  of  these  necks  of  orange- 
ochre  were  of  more  or  less  uniform  breadth 
throughout. 

The  long,  dark  streaks  that  in  June  had 
joined  the  Syrtis  Major  to  the  polar  sea  had 
by  October  nearly  disappeared  ;  in  their  south- 
ern parts  they  had  vanished  completely,  and 
they  had  very  much  faded  in  their  northern 
ones.  The  same  process  of  fading  uncovered 
certain  curious  rhomboidal  bright  areas  in  the 
midst  of  the  Syrtis  Major. 

It  will  be  seen  that  the  extent  of  these 
changes  was  enormous.  Their  size,  indeed,  was 
only  second  in  importance  to  their  character; 
for  it  will  also  have  been  noticed  that  the 
changes  were  all  in  one  direction.  A  whole- 
sale transformation  of  the  blue-green  regions 
into  orange-ochre  ones  was  in  progress  upon 
that  other  world. 

What  can  explain  so  general  and  so  consecu- 
tive a  change  in  hue  ?  Water  suggests  itself ; 
for  a  vast  transference  of  water  from  the  pole 
to  the  equator  might  account  for  it.  But  there 
are  facts  connected  with  the  change  which  seem 


120  MARS 

irreconcilable  with  the  idea  of  water.  In  the  first 
place,  Professor  W.  H.  Pickering  found  that  the 
light  from  the  great  blue-green  areas  showed  no 
trace  of  polarization.  This  tended  to  strengthen 
a  theory  put  forth  by  him  some  years  ago,  that 
the  greater  part  of  the  blue-green  areas  are  not 
water,  but  something  which  at  such  a  distance 
would  also  look  blue-green,  namely,  vegetation. 
Observations  at  Flagstaff  not  only  confirm  this, 
but  limit  the  water  areas  still  further ;  in  fact, 
practically  do  away  with  them  entirely.  Not 
only  do  the  above  polariscopic  tests  tend  to  this 
conclusion,  but  so  does  the  following  observa- 
tion of  mine  in  October. 

Toward  the  end  of  October,  a  strange,  and, 
for  observational  purposes,  a  distressing  phe- 
nomenon took  place.  What  remained  of  the 
more  southern  dark  regions  showed  a  desire  to 
vanish,  so  completely  did  those  regions  proceed 
to  fade  in  tint  throughout.  This  was  first  no- 
ticeable in  the  Cimmerian  Sea,  then  in  the  Sea 
of  the  Sirens,  and  in  November  in  the  Mare 
Erythraeum  about  the  Lake  of  the  Sun.  The 
fading  steadily  progressed  until  it  had  advanced 
so  far  that  in  poor  seeing  the  markings  were 
almost  imperceptible,  and  the  planet  presented 
a  nearly  uniform  ochre  disk. 

This  was  not  a  case  of  obscuration;  for  in 
the  first  place  it  was  general,  and  in  the  second 
place  the  coast-lines  were  not  obliterated.  The 


SEAS  121 

change,  therefore,  was  not  due  to  clouds  or 
mist. 

What  was  suggestive  about  the  occurrence 
was  that  it  was  unaccompanied  by  a  correspond- 
ing increase  of  blue-green  elsewhere.  It  was 
not  simply  that  portions  of  the  planet's  surface 
changed  tint,  but  that,  taking  the  disk  in  its 
entirety,  the  whole  amount  of  the  blue-green 
upon  it  had  diminished,  and  that  of  the  orange- 
yellow  had  proportionally  increased.  Mars 
looked  more  Martian  than  he  had  in  June. 
The  canals,  indeed,  began  at  the  same  time  to 
darken  ;  but,  highly  important  as  this  was  for 
other  reasons,  the  whole  area  of  their  fine  lines 
and  associated  patches  did  not  begin  to  make 
up  for  what  the  dark  regions  lost. 

If  the  blue-green  color  was  due  to  water, 
where  had  all  the  water  gone  ?  Nowhere  on 
the  visible  parts  of  the  planet ;  that  is  certain. 
Nor  could  it  very  well  have  gone  to  those  north 
circumpolar  regions  hid  from  view  by  the  tilt 
of  the  disk  ;  for  there  was  no  sign  of  a  growing 
north  polar  cap,  and,  furthermore,  Schiaparelli's 
observations  upon  that  cap  show  that  there 
should  not  have  been.  At  the  opposition  of 
1881,  he  found  that  it  developed  late,  appar- 
ently one  month  or  so  after  the  vernal  equinox 
of  its  hemisphere,  whereas  at  the  time  the  above 
change  occurred  it  was  not  long  after  that  hemi- 
sphere's winter  solstice. 


122  MARS 

But  if,  instead  of  being  due  to  water,  the 
blue-green  tint  had  been  due  to  leaves  and 
grasses,  just  such  a  fading  out  as  was  observed 
should  have  taken  place  as  autumn  came  on, 
and  that  without  proportionate  increase  of  green 
elsewhere ;  for  the  great  continental  areas,  be- 
ing desert,  are  incapable  of  supporting  vegeta- 
tion, and  therefore  of  turning  green. 

Thus  we  see  that  several  independent  phe- 
nomena all  agree  to  show  that  the  blue-green 
regions  of  Mars  are  not  water,  but,  generally 
at  least,  areas  of  vegetation ;  from  which  it  fol- 
lows that  Mars  is  very  badly  off  for  water,  and 
that  the  planet  is  dependent  on  the  melting  of 
its  polar  snows  for  practically  its  whole  supply. 

Such  scarcity  of  water  on  Mars  is  just  what 
theory  would  lead  us  to  expect.  Mars  is  a 
smaller  planet  than  the  Earth,  and  therefore  is 
relatively  more  advanced  in  his  evolutionary 
career.  He  is  older  in  age,  if  not  in  years ;  for 
whether  his  birth  as  a  separate  world  antedated 
ours  or  not,  his  smaller  size,  by  causing  him  to 
cool  more  quickly,  would  necessarily  age  him 
faster.  But  as  a  planet  grows  old,  its  oceans, 
in  all  probability,  dry  up,  the  water  retreating 
through  cracks  and  caverns  into  its  interior. 
Water  thus  disappears  from  its  surface,  to  say 
nothing  of  what  is  being  continually  imprisoned 
by  chemical  combination.  Signs  of  having  thus 
parted  with  its  oceans  we  see  in  the  case  of  the 


SEAS  123 

Moon,  whose  so-called  seas  were  probably  seas 
in  their  day,  but  have  now  become  old  sea- 
bottoms.  On  Mars  the  same  process  is  going 
on,  but  would  seem  not  yet  to  have  progressed 
so  far,  the  seas  there  being  midway  in  their 
career  from  real  seas  to  arid  depressed  deserts ; 
no  longer  water  surfaces,  they  are  still  the  low- 
est portions  of  the  planet,  and  therefore  stand 
to  receive  what  scant  water  may  yet  travel 
over  the  surface.  They  thus  become  fertilized, 
while  higher  regions  escape  the  freshet,  and 
remain  permanently  barren.  That  they  were 
once  seas  we  have  something  more  than  gen- 
eral inference  to  warrant  us  in  believing. 

There  is  a  certain  peculiarity  about  the  sur- 
face markings  of  Mars,  which  is  pretty  sure  to 
strike  any  thoughtful  observer  who  examines 
the  planet's  disk,  with  a  two-  or  a  three-inch 
object-glass, —  their  singular  sameness  night 
after  night.  With  quite  disheartening  regu- 
larity, each  evening  presents  him  with  the  same 
appearance  he  noted  the  evening  before,  —  a 
dark  band  obliquely  belting  the  disk,  strangely 
keeping  its  place  in  spite  of  the  nightly  pro- 
cession of  the  meridians  ten  degrees  to  the  east, 
in  consequence  of  our  faster  rotation  gaining 
on  the  slower  rotation  of  Mars.  By  attention, 
he  will  notice,  however,  that  the  belt  creeps 
slowly  upwards  towards  the  pole.  Then  sud- 
denly some  night  he  finds  that  it  has  slipped 


124  MARS 

bodily  down,  to  begin  again  its  Sisyphus-like, 
inconclusive  spiral  climb. 

Often  as  this  rhumb  line  must  have  been  no- 
ticed, no  explanation  of  it  has  ever,  to  my 
knowledge,  been  given.  Yet  so  singular  an  ar- 
rangement points  to  something  other  than 
chance.  Suspicion  of  its  non-fortuitous  charac- 
ter is  strengthened  when  it  is  scanned  through 
a  bigger  glass.  Increase  of  aperture  discloses 
details  that  help  explain  its  significance.  With 
sufficient  telescopic  power,  the  continuity  of  the 
dark  belt  is  seen  to  be  broken  by  a  series  of 
parallel  peninsulas  or  semi-peninsulas  that  jut 
out  from  the  lower  edge  of  the  belt,  all  running 
with  one  accord  in  a  southeasterly  direction, 
and  dividing  the  belt  into  a  similar  series  of 
parallel  dark  areas.  Such  oblong  areas  are  the 
Mare  Tyrrhenum,  the  Mare  Cirnmerium,  the 
Mare  Sirenum,  and  those  unnamed  straits  that 
stretch  southeasterly  from  the  Aurorae  Sinus, 
the  Margaritifer  Sinus,  and  the  Sabaeus  Sinus. 
The  islands  and  peninsulas  trending  in  the  same 
direction  are  Ausonia,  Hesperia,  Cimmeria, 
Atlantis,  Pyrrhae  Regio,  Deucalionis  Regio,  and 
the  two  causeways  from  the  Fastigium  Aryn 
and  Hammonis  Cornu.  It  will  further  be  no- 
ticed that  these  areas  lie  more  nearly  north 
and  south  as  they  lie  nearer  the  pole,  and 
curve  in  general  to  the  west  as  they  approach 
the  equator. 


SEAS  125 

With  this  fact  noted,  let  us  return  to  the 
water  formed  by  the  melting  of  the  ice-cap,  at 
the  time  it  is  produced  around  the  south  pole. 
We  may  be  sure  it  would  not  stay  there  long. 
No  sooner  liberated  from  its  winter  fetters  than 
it  would  begin,  under  the  pull  of  gravity,  to 
run  toward  the  equator.  The  reason  why  it 
would  flow  away  from  the  pole  is  that  it  would 
find  itself  in  unstable  equilibrium  where  it  was. 
Successive  depositions  of  frost  would  have  piled 
up  a  mound  of  ice  which,  so  long  as  it  remained 
solid,  cohesion  would  keep  in  that  unnatural 
position;  but  the  moment  it  changed  to  a  liquid 
this  would  flow  out  on  all  sides,  seeking  its 
level.  Once  started,  its  own  withdrawal  would 
cause  the  centre  of  gravity  to  shift  away  from 
the  pole,  and  this  would  pull  the  particles  of 
the  water  yet  more  toward  the  equator.  Each 
particle  would  start  due  north ;  but  its  course 
would  not  continue  in  that  direction,  for  at  each 
mile  it  traveled  it  would  find  itself  in  a  lower 
latitude,  where,  owing  to  the  rotation  of  the 
planet,  the  surface  would  be  whirling  faster  to- 
ward the  east,  inasmuch  as  a  point  on  the  equa- 
tor has  to  get  over  much  more  space  in  twenty- 
four  hours  than  one  nearer  the  pole.  In  short, 
supposing  there  were  no  friction,  the  surface 
would  be  constantly  slipping  away  from  under 
the  particle  toward  the  east.  As  a  result,  the 
northerly  motion  of  the  particle  would  be  con- 


126  MARS 

tinually  changing  with  regard  to  the  surface  into 
a  more  and  more  westerly  one.  If  the  surface 
were  not  frictionless,  friction  would  somewhat 
reduce  the  westerly  component,  but  could  never 
wholly  destroy  it  without  stopping  the  particle. 

We  see,  therefore,  that  any  body,  whether 
solid,  liquid,  or  gaseous,  must,  in  traveling  away 
from  the  pole  of  a  sphere  or  spheroid,  neces- 
sarily deviate  to  the  west  as  it  goes  on,  if  the 
spheroid  itself  revolve,  as  Mars  does,  in  the  op- 
posite direction. 

Now  this  inevitable  trend  induced  in  any- 
thing flowing  from  the  pole  to  the  equator  is 
precisely  the  one  that  we  notice  stereotyped  so 
conspicuously  in  the  Martian  south  temperate 
markings.  Here,  then,  we  have  at  once  a 
suspiciously  suggestive  hint  that  they  once  held 
water,  and  that  that  water  flowed. 

Corroborating  this  deduction  is  the  fact  that 
the  northern  sides  of  all  the  dark  areas  are  very 
perceptibly  darker  than  the  southern  ones ;  for 
the  northern  side  is  the  one  which  a  descending 
current  would  plough  out,  since  it  is  the  north- 
ern coasts  that  would  be  constantly  opposing 
the  current's  northerly  inertia.  Consequently, 
although  at  present  the  descending  stream  be 
quite  inadequate  to  such  task,  it  still  finds  its 
way,  from  preference,  to  these  lowest  levels, 
and  makes  them  greener  than  the  rest. 

Though  seas   no  longer,  we   perceive,  then, 


SEAS  127 

that  there  is  some  reason  to  believe  the  so-called 
seas  of  Mars  to  have  been  seas  in  their  day,  and 
to  be  at  the  present  moment  midway  in  evo- 
lution from  the  seas  of  Earth  to  the  seas  of  the 
Moon. 

Now,  if  a  planet  were  at  any  stage  of  its 
career  able  to  support  life,  it  is  probable 
that  a  diminishing  water  supply  would  be  the 
beginning  of  the  end  of  that  life,  for  the  air 
would  outlast  the  available  water.  Those  of 
its  inhabitants  who  had  succeeded  in  surviving 
would  find  themselves  at  last  face  to  face  with 
the  relentlessness  of  a  scarcity  of  water  con- 
stantly growing  greater,  till  at  last  they  would 
all  die  of  thirst,  either  directly  or  indirectly ; 
for  either  they  themselves  would  not  have 
water  enough  to  drink,  or  the  plants  or  animals 
which  constituted  their  diet  would  perish  for 
lack  of  it,  —  an  alternative  of  small  choice  to 
them,  unless  they  were  conventionally  particular 
as  to  their  mode  of  death.  Before  this  lament- 
able conclusion  was  reached,  however,  there 
would  come  a  time  in  the  course  of  the  planet's 
history  when  water  was  not  yet  wanting,  but 
simply  scarce  and  requiring  to  be  husbanded  ; 
when,  for  the  inhabitants,  the  one  supreme 
problem  of  existence  would  be  the  water  prob- 
lem, —  how  to  get  water  enough  to  sustain  life, 
and  how  best  to  utilize  every  drop  of  water 
they  could  get. 


128  MARS 

Mars  is,  apparently,  in  this  distressing  plight 
at  the  present  moment,  the  signs  being  that  its 
water  supply  is  now  exceedingly  low.  If, 
therefore,  the  planet  possess  inhabitants,  there 
is  but  one  course  open  to  them  in  order  to  sup- 
port life.  Irrigation,  and  upon  as  vast  a  scale 
as  possible,  must  be  the  all-engrossing  Martian 
pursuit.  So  much  is  directly  deducible  from 
what  we  have  learned  at  Flagstaff  of  the  phy- 
sical condition  of  the  planet,  quite  apart  from 
any  question  as  to  possible  inhabitants.  What 
the  physical  phenomena  assert  is  this  :  if  there 
be  inhabitants,  then  irrigation  must  be  the  chief 
material  concern  of  their  lives. 

At  this  point  in  our  inquiry,  when  direct  de- 
duction from  the  general  physical  phenomena 
observable  on  the  planet's  surface  shows  that, 
were  there  inhabitants  there,  a  system  of  irriga- 
tion would  be  an  all-essential  of  their  existence, 
the  telescope  presents  us  with  perhaps  the  most 
startling  discovery  of  modern  times,  —  the  so- 
called  canals  of  Mars.  These  strange  pheno- 
mena, together  with  the  inferences  to  be  drawn 
from  them,  we  will  now  proceed  to  envisage. 


IV 

CANALS 

I.    FIRST   APPEARANCES 

IN  the  last  chapter  we  saw  how  badly  off  for 
water  Mars,  to  all  appearance,  is ;  so  badly  off 
that  inhabitants  of  that  other  world  would  have 
to  irrigate  to  live.  As  to  the  actual  presence 
there  of  such  folk,  the  broad  physical  character- 
istics of  the  planet  express  no  opinion  beyond 
the  silence  of  consent,  but  they  have  some- 
thing very  vital  to  say  about  the  conditions 
under  which  alone  their  life  could  be  led.  They 
show  that  these  conditions  must  be  such  that  in 
the  Martian  mind  there  would  be  one  question 
perpetually  paramount  to  all  the  local  labor, 
women's  suffrage,  and  Eastern  questions  put  to- 
gether —  the  water  question.  How  to  procure 
water  enough  to  support  life  would  be  the  great 
communal  problem  of  the  day. 

Were  Mars  like  the  Earth,  we  might  well  de- 
spair of  detecting  signs  of  any  Martians  for 
some  time  yet.  Across  the  gulf  of  space  that 
separates  us  from  Mars,  an  area  thirty  miles 
wide  would  just  be  perceptible  as  a  dot.  It 


130  MARS 

would,  in  such  case,  be  hopeless  to  look  for  evi- 
dence of  folk.  Anything  like  London  or  New 
York,  or  even  Chicago  in  its  own  estimation, 
would  be  too  small  to  be  seen,  so  sorry  a  fig- 
ure does  man  cut  upon  the  Earth  he  thinks  to 
own.  From  the  standpoint  of  forty  millions  of 
miles  distance,  probably  the  only  sign  of  his 
presence  here  would  be  such  semi-artificialities 
as  the  great  grain-fields  of  the  West  when  their 
geometric  patches  turned  with  the  changing 
seasons  from  ochre  to  green,  and  then  from 
green  to  gold.  By  his  crops  we  should  know 
him.  A  tell-tale  fact  this,  for  it  would  be  still 
more  likely  to  be  the  case  with  Mars.  If  the 
surface  of  the  planet  were  cultivated  at  all,  it 
would  probably  be  upon  a  much  more  thorough 
plan  than  is  the  case  with  the  Earth.  Condi- 
tions hold  there  which  would  necessitate  a  much 
more  artificial  state  of  things.  If  cultivation 
there  be,  it  must  be  cultivation  largely  depend- 
ent upon  a  system  of  irrigation,  and  therefore 
much  more  systematic  than  any  we  have  as 
yet  been  forced  to  adopt. 

Now,  at  this  point  in  our  investigation,  when 
the  broad  features  of  Mars  disclose  conditions 
which  imply  irrigation  as  their  organic  corol- 
lary, we  are  suddenly  confronted  on  the  planet's 
face  with  phenomena  so  startlingly  suggestive 
of  this  very  thing  as  to  seem  its  uncanny  pre- 
sentment. Indeed,  so  amazingly  lifelike  is  their 


CANALS  131 

appearance  that,  had  we  possessed  our  present 
knowledge  of  the  planet's  physical  condition 
before,  we  might  almost  have  predicted  what 
we  see  as  criterion  of  the  presence  of  living 
beings.  What  confronts  us  is  this  :  — 

When  the  great  continental  areas,  the  reddish- 
ochre  portions  of  the  disk,  are  attentively  ex- 
amined in  sufficiently  steady  air,  their  desert- 
like  ground  is  seen  to  be  traversed  by  a  network 
of  fine,  straight,  dark  lines.  The  lines  start 
from  points  on  the  coast  of  the  blue-green  re- 
gions, commonly  well-marked  bays,  and  proceed 
directly  to  what  seem  centres  in  the  middle  of 
the  continent,  since  most  surprisingly  they  meet 
there  other  lines  that  have  come  to  the  same 
spot  with  apparently  a  like  determinate  intent. 
And  this  state  of  things  is  not  confined  to  any 
one  part  of  the  planet,  but  takes  place  all  over 
the  reddish-ochre  regions. 

The  lines  appear  either  absolutely  straight 
from  one  end  to  the  other,  or  curved  in  an 
equally  uniform  manner.  There  is  nothing 
haphazard  in  the  look  of  any  of  them.  Plotting 
upon  a  globe  betrays  them  to  be  arcs  of  great 
circles  almost  invariably,  even  the  few  outstand- 
ing exceptions  seeming  to  be  but  polygonal 
combinations  of  the  same.  Their  most  instantly 
conspicuous  characteristic  is  this  hopeless  lack 
of  happy  irregularity.  They  are,  each  and  all, 
direct  to  a  degree. 


132  MARS 

The  lines  are  as  fine  as  they  are  straight. 
As  a  rule,  they  are  of  scarcely  any  perceptible 
breadth,  seeming  on  the  average  to  be  less  than 
a  Martian  degree,  or  about  thirty  miles  wide. 
They  differ  slightly  among  themselves,  some 
being  a  little  broader  than  this ;  some  a  trifle 
finer,  possibly  not  above  fifteen  miles  across. 
Their  length,  not  their  breadth,  renders  them 
visible ;  for  though  at  such  a  distance  we  could 
not  distinguish  a  dot  less  than  thirty  miles  in 
diameter,  we  could  see  a  line  of  much  less 
breadth,  because  of  its  length.  Speaking  gen- 
erally, however,  the  lines  are  all  of  comparable 
width. 

Still  greater  uniformity  is  observable  in  dif- 
ferent parts  of  the  same  line ;  for  each  line 
maintains  its  individual  width,  from  one  end  of 
its  course  to  the  other.  Although,  at  and  near 
the  point  where  it  leaves  the  dark  regions,  some 
slight  enlargement  seems  to  occur,  after  it  has 
fairly  started  on  its  course,  it  remains  of  substan- 
tially the  same  size  throughout.  As  to  whether 
the  lines  are  even  on  their  edges  or  not,  I 
should  not  like  to  say ;  but  the  better  they  are 
seen,  the  more  even  they  look.  It  is  not  possi- 
ble to  affirm  positively  on  the  point,  as  they  are 
practically  nearer  one  dimension  than  two. 

On  the  other  hand,  their  length  is  usually 
great,  and  in  cases  enormous.  A  thousand  or 
fifteen  hundred  miles  may  be  considered  about 


CANALS  133 

the  average.  The  Ganges,  for  example,  which 
is  not  a  long  one  as  Martian  canals  go,  is  about 
1,450  miles  in  length.  The  Brontes,  one  of  the 
newly  discovered,  radiating  from  the  Gulf  of 
the  Titans,  extends  over  2,400  miles;  while, 
among  really  long  ones,  the  Eumenides,  with 
its  continuation  the  Orcus,  the  two  being  in 
truth  one  line,  measures  3,540  miles  from  the 
point  where  it  leaves  the  Phoenix  Lake  to  the 
point  where  it  enters  the  Trivium  Charontis,  — 
throughout  this  whole  distance,  nearly  equal  to 
the  diameter  of  the  planet,  deviating  neither  to 
the  right  nor  to  the  left  from  the  great  circle 
upon  which  it  set  out.  On  the  other  hand,  the 
shortest  line  is  the  Nectar,  which  is  only  about 
250  miles  in  length ;  sweetness  being,  according 
to  Schiaparelli  its  christener,  as  short-lived  on 
Mars  as  elsewhere. 

That,  with  very  few  exceptions,  the  lines  all 
follow  arcs  of  great  circles  is  proved,  —  first,  by 
the  fact  that,  when  not  too  long,  they  show  as 
straight  lines;  second,  that,  when  seen  near 
the  limb,  they  appear  curved,  in  keeping  with 
the  curvature  of  a  spherical  surface  viewed 
obliquely;  third,  that,  when  the  several  parts 
of  some  of  the  longer  lines  are  plotted  upon  a 
globe,  they  turn  out  to  lie  in  one  great  circle. 
Apparent  straightness  throughout  is  only  possi- 
ble in  comparatively  short  lines.  For  a  very 
long  arc  upon  the  surface  of  a  revolving  globe 


134  MARS 

tilted  toward  the  observer  to  appear  straight  in 
its  entirety,  it  must  lie  due  north  and  south. 
Such,  of  course,  is  rarely  the  case.  It  so  chances, 
however,  that  these  conditions  are  fulfilled  by 
the  great  canal  called  the  Titan.  The  Titan 
starts  from  the  Gulf  of  the  Titans,  in  south  lati- 
tude 20°,  and  runs  north  almost  exactly  upon 
the  169th  meridian  for  an  immense  distance.  I 
have  followed  it  over  2,300  miles  down  the  disk 
to  about  43°  north,  as  far  as  the  tilt  of  the 
planet's  axis  would  permit.  As  the  rotation  of 
the  planet  swings  it  round,  it  passes  the  central 
meridian  of  the  disk  simultaneously  throughout 
its  length,  and  at  that  moment  comes  out  so 
strikingly  straight  it  seems  a  substantialized 
meridian  itself. 

Although  each  line  is  the  arc  of  a  great  circle, 
the  direction  taken  by  this  great  circle  may  be 
any  whatsoever.  The  Titan,  as  we  have  seen, 
runs  nearly  due  north  and  south.  Certain 
canals  crossing  this  run,  on  the  contrary,  al- 
most due  east  and  west.  There  are  others, 
again,  belting  the  disk  at  well-nigh  every  angle 
between  these  two  extremes.  Nor  is  there  any 
preponderance,  apparently,  for  one  direction  as 
against  any  other.  This  indifference  to  direc- 
tion is  important  as  showing  that  the  rotation 
of  the  planet  has  no  bearing  upon  the  inclina- 
tion of  the  canals. 

But,  singular  as  each  line  looks  to  be  by  it- 


CANALS  135 

self,  it  is  the  systematic  network  of  the  whole 
'that  is  most  amazing.  Each  line  not  only  goes 
with  wonderful  directness  from  one  point  to 
another,  but  at  this  latter  spot  it  contrives  to 
meet,  exactly,  another  line  which  has  come  with 
like  directness  from  quite  a  different  direction. 
Nor  do  two  only  manage  thus  to  rendezvous. 
Three,  four,  five,  and  even  seven  will  similarly 
fall  in  on  the  same  spot,  —  a  gregariousness 
which,  to  a  greater  or  less  extent,  finds  effec- 
tive possibility  all  over  the  surface  of  the  planet. 
The  disk  is  simply  a  network  of  such  inter- 
sections. Sometimes  a  canal  goes  only  from 
one  intersection  to  another;  more  commonly 
it  starts  with  right  of  continuation,  and,  after 
reaching  the  first  rendezvous,  goes  on  in  un- 
changed course  to  several  more. 

The  result  is  that  the  whole  of  the  great 
reddish-ochre  portions  of  the  planet  is  cut  up 
into  a  series  of  spherical  triangles  of  all  possible 
sizes  and  shapes.  What  their  number  may  be 
lies  quite  beyond  the  possibility  of  count  at 
present ;  for  the  better  our  own  air,  the  more 
of  them  are  visible.  About  four  times  as  many 
as  are  down  on  Schiaparelli's  chart  of  the  same 
regions  have  been  seen  at  Flagstaff.  But,  be- 
fore proceeding  further  with  a  description  of 
these  Martian  phenomena,  the  history  of  their 
discovery  deserves  to  be  sketched  here,  since  it 
is  as  strange  as  the  canals  themselves. 


136  MAES 

The  first  hint  the  world  had  of  their  exist- 
ence was  when  Schiaparelli  saw  some  of  the 
lines  in  1877,  now  eighteen  years  ago.  The 
world,  however,  was  anything  but  prepared  for 
the  revelation,  and,  when  he  announced  what 
he  had  seen,  promptly  proceeded  to  disbelieve 
him.  Schiaparelli  had  the  misfortune  to  be 
ahead  of  his  times,  and  the  yet  greater  misfor- 
tune to  remain  so ;  for  not  only  did  no  one  else 
see  the  lines  at  that  opposition,  but  no  one 
else  succeeded  in  doing  so  at  subsequent  ones. 
For  many  years  fate  allowed  Schiaparelli  to 
have  them  all  to  himself,  a  confidence  he  amply 
repaid.  While  others  doubted,  he  went  from 
discovery  to  discovery.  What  he  had  seen  in 
1877  was  not  so  very  startling  in  view  of  what 
he  afterward  saw.  His  first  observations  might 
well  have  been  of  simple  estuaries,  long  natural 
creeks  running  up  into  the  continents,  and  even 
cutting  them  in  two.  His  later  observations 
were  too  peculiar  to  be  explained,  even  by  so  im- 
probable a  configuration  of  the  Martian  surface. 
In  1879  the  canali,  as  he  called  them  (channels, 
or  canals,  the  word  may  be  translated,  and  it  is 
in  the  latter  sense  that  he  now  regards  them), 
showed  straighter  and  narrower  than  they  had 
in  1877 :  this  not  in  consequence  of  any  change 
in  them,  but  from  his  own  improved  faculty  of 
detection;  for  what  the  eye  has  once  seen  it 
can  always  see  better  a  second  time.  As  he 


CANALS  137 

gazed  they  appeared  straighter,  and  he  made 
out  more.  Lastly,  toward  the  end  of  the  year, 
he  observed  one  evening  what  struck  even  him 
as  a  most  startling  phenomenon,  —  the  twin- 
ning of  one  of  the  canals :  two  parallel  canals 
suddenly  showed  where  but  a  single  one  had 
showed  before.  The  paralleling  was  so  perfect 
that  he  suspected  optical  illusion.  He  could, 
however,  discover  none  by  changing  his  tele- 
scopes or  eye-pieces.  The  phenomenon,  appar- 
ently, was  real. 

At  the  next  opposition  he  looked  to  see  if 
by  chance  he  should  mark  a  repetition  of  the 
strange  event,  and  went,  as  he  tells  us,  from 
surprise  to  surprise;  for  one  after  another  of 
his  canals  proceeded  startlingly  to  become  two, 
until  some  twenty  of  them  had  thus  doubled. 
This  capped  the  climax  to  his  own  wonderment, 
and,  it  is  needless  to  add,  to  other  people's  in- 
credulity ;  for  nobody  else  had  yet  succeeded 
in  seeing  the  canals  at  all,  let  alone  seeing  them 
double.  Undeterred  by  the  general  skepticism, 
he  confirmed  at  each  fresh  opposition  his  pre- 
vious discoveries,  which,  in  view  of  the  fact  that 
no  one  else  did,  tended  in  astronomical  circles 
to  an  opposite  result. 

For  nine  years  he  labored  thus  alone,  having 
his  visions  all  to  himself.  It  was  not  till  1886 
that  any  one  but  he  saw  the  canals.  In  April 
of  that  year  Perrotin,  at  Nice,  first  did  so.  The 


138  MARS 

occasion  was  the  setting  up  of  the  great  Nice 
glass  of  twenty-nine  inches  aperture.  In  spite 
of  the  great  size  of  the  glass,  however,  a  first 
attempt  resulted  in  nothing  but  failure.  So, 
later,  did  a  second,  and  Perrotin  was  on  the 
point  of  abandoning  the  search  for  good,  when, 
on  the  15th  of  the  month,  he  suddenly  detected 
one  of  the  canals,  the  Phison.  His  assistant, 
M.  Thollon,  saw  it  immediately  afterward.  After 
this  they  managed  to  make  out  several  others, 
some  single,  some  double,  substantially  as  Schia- 
parelli  had  drawn  them ;  the  slight  discrep- 
ancies between  their  observations  and  his  being 
in  point  of  fact  the  best  of  confirmations. 

Since  then,  other  observers  have  contrived  to 
detect  the  canals,  the  list  of  the  successful  in- 
creasing at  each  opposition,  although  even  now 
their  number  might  almost  be  told  on  one's 
hands  and  feet. 

The  reason  that  so  few  astronomers  have  as 
yet  succeeded  in  seeing  these  lines  is  to  be 
found  in  our  own  atmosphere.  That  in  ordi- 
nary atmosphere  the  lines  are  not  easy  objects 
is  certain.  A  moderately  good  air  is  essential 
to  their  detection ;  and  unfortunately  the  loca- 
tions of  most  of  our  observatories  preclude  this 
prerequisite.  Size  of  aperture  of  the  telescope 
used  is  a  very  secondary  matter.  That  Schia- 
parelli  discovered  the  canals  with  an  8^-inch 
glass,  and  that  the  26-inch  glass  at  Washington 


PLATE  XVIII 


-' 


FASTIGIUM   ARYN 
OCTOBER,  1894 


CANALS  139 

has  refused  to  show  them  to  this  day,  are  facts 
that  speak  emphatically  on  the  point. 

The  importance  of  atmosphere  in  the  study 
of  planetary  detail  is  far  from  being  appre- 
ciated. It  is  not  simply  question  of  a  clear 
air,  but  of  a  steady  one.  To  detect  fine  detail, 
the  atmospheric  strata  must  be  as  evenly  dis- 
posed as"  possible. 

Next  in  importance  to  a  steady  air  comes  at- 
tentive perception  on  the  part  of  the  observer. 
The  steadiest  air  we  can  find  is  in  a  state  of 
almost  constant  fluctuation.  In  consequence, 
revelations  of  detail  come  only  to  those  who 
patiently  watch  for  the  few  good  moments 
among  the  many  poor.  Nor  do  I  believe  even 
average  air  to  be  entirely  without  such  happy 
exceptions  to  a  general  blur.  In  these  brief 
moments  perseverance  will  show  the  canals  as 
faint  streaks.  To  see  them  as  they  are,  how- 
ever, an  atmosphere  possessing  moments  of 
really  distinct  vision  is  imperative.  For  the 
canals  to  come  out  in  all  their  fineness  and 
geometrical  precision,  the  air  must  be  steady 
enough  to  show  the  markings  on  the  planet's 
disk  with  the  clear-cut  character  of  a  steel  en- 
graving. No  one  who  has  not  seen  the  planet 
thus  can  pass  upon  the  character  of  these  lines. 

Although  skepticism  as  to  the  existence  of 
the  so-called  canals  has  been  now  pretty  well 
dispelled  by  these  and  other  observations,  dis- 


140  MARS 

belief  still  makes  a  desperate  stand  against  their 
peculiar  appearance,  dubbing  accounts  of  their 
straightness  and  duplication  as  sensational,  what- 
ever they  may  mean  in  such  connection;  for 
that  they  are  both  straight  and  double,  as  de- 
scribed, is  certain,  —  a  statement  I  make  after 
having  seen  them,  instead  of  before  doing  so,  as 
is  the  case  with  the  gifted  objectors.  Doubt, 
however,  will  not  wholly  cease  till  more  peo- 
ple have  seen  them,  which  will  not  happen  till 
the  importance  of  atmosphere  in  the  study  of 
planetary  detail  is  more  generally  appreciated 
than  it  is  to-day.  To  look  for  the  canals  with 
a  large  instrument  in  poor  air  is  like  trying  to 
read  a  page  of  fine  print  kept  dancing  before 
one's  eyes,  with  the  additional  disadvantage 
that  increase  of  magnification  increases  the  mo- 
tion. Advance  in  our  study  of  other  worlds 
depends  upon  choosing  the  very  best  atmos- 
pheric sites  for  our  observatories. 

It  is  interesting  to  recall,  in  connection  with 
this  incredulity  about  the  canals,  that  precisely 
the  same  thing  happened  in  the  case  of  the  dis- 
covery of  Jupiter's  satellites  and  with  Huy- 
ghens'  explanation  of  Saturn's  ring.  "We  are 
apt  to  imagine  that  our  age  of  the  world  has  a 
monopoly  of  skepticism.  But  this  is  a  mistake. 
The  spirit  that  denies  has  always  been  abroad ; 
only  in  early  days  he  was  reputed  to  be  the 
devil. 


MAP  AND  CATALOGUE  141 

II.    MAP   AND    CATALOGUE 

As  we  shall  now  have  to  call  these  Martian 
things  by  their  names,  —  our  names,  that  is,  — 
it  may  be  well  to  consider  cursorily  the  nomen- 
clature which  has  been  evolved  on  the  subject. 
Unfortunately,  the  planet  has  been  quite  too 
much  benamed,  —  benamed,  indeed,  out  of  all 
recognition.  There  are  no  less  than  five  or  six 
systems  current  for  its  general  topographical 
features.  The  result  is  that  it  has  become 
something  of  a  specialty  just  to  know  the 
names.  The  Syrtis  Major,  for  example,  appears 
under  the  following  aliases :  the  Syrtis  Major, 
the  Mer  du  Sablier,  the  Kaiser  Sea,  the  North- 
ern Sea,  to  say  nothing  of  translations  of  these, 
such  as  the  Hourglass  Sea ;  after  which  ample 
baptism  it  is  a  trifle  disconcerting  to  have  the 
sea  turn  out,  apparently,  not  to  be  a  sea  at  all. 
Everybody  has  tried  his  hand  at  naming  the 
planet,  first  and  last ;  naming  a  thing  being 
man's  nearest  approach  to  creating  it.  Proctor 
made  a  chart  of  the  planet,  and  named  it 
thoroughly ;  Flammarion  made  another  chart, 
and  also  named  it  thoroughly,  but  differently  ; 
Green  drew  a  third  map,  and  gave  it  a  third  set 
of  names ;  Schiaparelli  followed  with  a  fourth, 
and  furnished  it  with  a  brand-new  set  of  his 
own ;  and  finally  W.  H.  Pickering  found  it 
necessary  to  give  a  few  new  names,  just  for 


142  MARS 

particularization.  To  know,  therefore,  what 
part  of  the  planet  anybody  means  when  he 
mentions  it,  one  has  to  keep  in  his  head  enough 
names  for  five  worlds.  To  cap  which,  it  is  to 
be  remarked  that  not  one  of  them  is  the  thing's 
real  —  that  is,  its  Martian  —  name,  after  all ! 

Fortunately,  with  the  canals,  matters  are  not 
so  desperate,  because  so  few  people  have  seen 
them.  Schiaparelli's  monopoly  of  the  sight 
pleasingly  prevented,  in  their  case,  christening 
competition.  What  is  more,  he  named  them, 
very  judiciously  and  most  picturesquely,  after 
mythologic  river  names.  Where  he  got  his 
names  is  another  matter.  Whether  he  started 
by  being  as  learned  in  such  lore  as  he  afterward 
became  may  well  be  doubted.  Certainly,  one 
of  the  greatest  discoveries  made  at  Flagstaff  has 
been  the  discovery  of  the  meaning  of  Schiapa- 
relli's names;  some  of  them  still  defying  the 
penetrating  power  of  the  ordinary  encyclopae- 
dia. Among  them  are  classical  mythologic  ones 
of  the  class  known  only  to  that  himself  myth- 
ical '  character,  Macaulay's  every  schoolboy ; 
which  speaks  conclusively  for  their  recondite- 
ness.  Others,  I  firmly  believe,  even  that  om- 
niscient schoolboy  can  never  have  heard  of. 
Want  of  space  here  precludes  instances  ;  but  as 
a  simple  example  I  may  say  that  the  translation 
to  Mars  of  the  Phison  and  the  Gihon,  the  two 
lost  rivers  of  Mesopotamia,  satisfactorily  ac* 


MAP  AND  CATALOGUE  143 

counts  for  their  not  being  found  on  earth  by 
modern  explorers. 

With  due  mental  reservation  as  to  their 
meaning,  I  have  adopted  Schiaparelli's  names, 
and,  where  it  has  been  necessary  to  name  newly 
discovered  canals,  have  conformed  as  closely  as 
possible  to  his  general  scheme.  If,  even  in  an 
instance  or  two,  I  have  hit  upon  names  that  are 
incomprehensible,  I  shall  feel  that  I  have  not  dis- 
graced my  illustrious  predecessor.  For  a  brand- 
new  thing  no  name  is  so  good  as  one  whose 
meaning  nobody  knows,  except  one  that  has  no 
meaning  at  all.  In  that  case  the  name  not  only 
is  becoming  but  actually  becomes  the  thing. 

These  names  will  be  found  affixed  to  their 
respective  canals  in  the  map  at  the  end  of  the 
book,  a  map  made  upon  what  is  called  Merca- 
tor's  projection.  Mercator's  projection  I  take  to 
have  been  primarily  an  invention  of  the  devil, 
although  commonly  credited  to  Mercator.  It  is 
not  simple  to  construct  and  for  popular  purposes 
is  eminently  deceitful.  It  is  intended  for  those 
at  sea,  whom  we  pray  for  on  Sundays.  It  is  cer- 
tainly calculated  to  put  any  one  entirely  at  sea 
who  attempts  to  learn  geography  by  means  of  it. 
Its  object  is  to  enable  such  as  wish  to  do  so  to  sail 
upon  rhumb  lines,  a  rhumb  line  upon  a  sphere 
being  one  which  never  changes  its  direction,  — 
one,  for  example,  which  runs  perpetually  north- 
east one  quarter  east,  or  south  half  west. 


144  MARS 

These  lines,  important  in  navigation,  are  in 
reality  diminishing  corkscrew-like  spirals,  but 
on  this  projection  become  straight  lines  which 
can  be  instantly  laid  down  by  rule  and  compass. 
To  make  such  delineation  possible  it  is  neces- 
sary to  distort  the  proportions  of  every  part  of 
the  map,  in  increasing  divergence  toward  the 
poles,  with  the  lamentable  result  that  in  early 
life  we  all  believed  Nova  Zembla  to  be  a  place 
as  big  as  South  America.  Nevertheless  Merca- 
tor's  projection  has  certain  advantages  not  so 
obvious  to  the  uninitiated,  nor  requiring  special 
mention  here.  In  this  connection  it  is  only 
necessary  to  warn  the  reader,  in  the  case  of  a 
geography  with  which  he  is  not  familiar,  like 
that  of  Mars,  to  remember  that  the  top  and 
bottom  of  the  map  are  drawn  upon  a  scale 
three  or  four  times  as  large  as  the  middle  ;  and, 
furthermore,  that  it  is  a  consequence  of  Merca- 
tor's  projection  that  arcs  of  great  circles  appear 
upon  it,  not  as  straight  lines,  but  as  curves  al- 
ways more  or  less  concave  to  the  equator.  For 
relative  size  of  the  various  features,  he  will  find 
the  twelve  views  from  the  globe  accurate ;  but 
for  the  impressiveness  of  the  great  circle  char- 
acter of  the  canals,  nothing  short  of  a  globe  it- 
self will  give  him  adequate  realization. 

The  map  represents  that  part  of  the  planet 
lying  between  latitudes  70°  south  and  about 
40°  north.  The  south  circumpolar  regions  will 


MAP  AND  CATALOGUE 


145 


be  found  in  the  chart  of  the  south  pole  facing 
page  84.  The  northern  ones  were  not  pre- 
sented to  view  at  the  last  opposition,  owing  to 
the  tilt  toward  us  of  the  Martian  south  pole. 
No  canals,  therefore,  north  of  about  40°  north 
latitude  were  visible. 

The  list  of  the  canals  detected  at  Flagstaff  is 
as  follows  : 


No.  of  drawings  in 

No.  of  drawings  in 

Name. 

which  it  appears. 

Name. 

which  it  appears. 

Acalandrus 

19 

Astaboras 

7 

Acampsis 

7 

Astapus 

29 

Acesines 

19 

Atax 

8  (Sus.  1) 

Achana 

1 

Athesis 

16 

Achates 

9 

Avernus 

14 

Achelous 

20 

Avus 

8 

Acheron 

11 

Axius 

9 

Acis 

14 

Axon 

2 

Aeolus 

13 

Bactrus 

2  (Sus.  1) 

Aesis 

23 

Baetis 

3 

Aethiops 

16 

Bathys 

69 

Agathodaemon 

127 

Bautis 

(Sus.  1) 

Alpheus 

4  (Sus,  3) 

Belus 

3 

Ambrosia 

36 

Boreas 

11 

Amenthes 

26 

Boreosyrtis 

4 

Amphrysus 

1 

Brontes 

38 

Amystis 

15 

Caicus 

8 

Anapus 

7 

Cambyses 

34 

Antaeus 

2  (Sus.  1) 

Cantabras 

7 

Anubis 

9 

Carpis 

3 

Araxes 

93  (Sus.  1) 

Casuentus 

21 

Arges 

2 

Catarrhactes 

3 

Arosis 

8 

Cayster 

3 

Arsanias 

1 

Centrites 

27 

Artanes 

9 

Cephissus 

35 

Asopus 

5                   Cerberus 

44  (Sus.  1) 

146 


MARS 


No.  of  drawings  in 

No.  of  drawings  in 

Name. 

which  it  appears. 

ixame. 

which  it  appears. 

Cestrus 

2 

Gaesus 

2 

Chaboras 

4 

Galaesus 

6 

Chretes 

14 

Galaxias 

28 

Chrysas 

6 

Ganges 

82 

Chrysorrhoas 

18 

Ganymede 

19 

Cinyphus 

14 

Garrhuenus 

12 

Clitumnus 

7 

Gehon 

11 

Clodianus 

1 

Gigas 

60  (Sus.  2) 

Cophen 

5 

Glaucus 

2 

Coprates 

41 

Gorgon 

33 

Corax 

33 

Gyes 

15 

Cyaneus 

6 

Hades 

22 

Cyrus 

3 

Halys 

4 

Daemon 

118 

Harpasus 

2 

Daix 

2  (Sus.  1) 

Hebe 

37 

Daradax 

6 

Helisson 

12 

Dardanus 

15 

Heratemis 

4 

Dargamanes 

20 

Herculis  Columnae  5 

Deuteronilus 

11 

Hiddekel 

18 

Digentia 

2 

Hipparis 

19 

Dosaron 

10 

Hippus 

13 

Drahonus 

5 

Hyctanis 

4 

Elison 

3 

Hydaspes 

1 

Eosphorus 

56  (Sus.  3) 

Hydraotes 

23 

Erannoboas 

17 

Hydriacus 

1 

Erebus 

21  (Sus.  1) 

Hylias 

7 

Erinaeus 

16 

Hyllus 

14 

Erymanthus 

21 

Hyphasis 

7  (Sus.  3) 

Erynnis 

3  (Sus.  1) 

Hypsas 

6 

Eulaeus 

1 

Hyscus 

13 

Eumenides 

103 

Indus 

10 

Eunostos 

12 

Iris 

7 

Euphrates 

36 

Isis 

5 

Eurymedon 

3 

Jamuna 

39 

Eurypus 

9 

Jaxartes 

23 

Evenus 

9 

Labotas 

8 

Fortunae 

10 

Laestrygon 

41 

MAP  AND  CATALOGUE 


147 


Name. 

No.  of  drawings  in 
which  it  appears. 

Name. 

No.  of  drawings  in 
which  it  appears. 

Leontes 

2 

Palamnus 

9 

Lethes 

19 

Parcae 

19  (Sus.  1) 

Liris 

13 

Peneus 

3  (Sus.  2) 

Maeander 

6 

Phasis 

29 

Magon 

2 

Phison 

56 

Malva 

8 

Proton  ilus 

11 

Margus 

1 

Psychrus 

5 

Medus 

2 

Pyriphlegethon 

53  (Sus.  1) 

Medusa 

24 

Scamander 

21 

Mogrus 

2 

Sesamus 

7 

Nectar 

87 

Simois 

5 

Neda 

2 

Sirenius 

60 

Nepenthes 

21 

Sitacus 

3 

Nereides 

8 

Steropes 

46 

Nestus 

5 

Styx 

7 

Neudrus 

10 

Surius 

6 

Nilokeras 

16 

Tartarus 

42 

Nilosyrtis 

21 

Tedanius 

25 

Nilus 

6 

Thermodon 

2 

Nymphaeus 

4 

Thyanis 

1 

Oceanus 

37 

Titan 

38 

Ochus 

3 

Tithonius 

77 

Opharus 

13 

Triton 

8 

Ore  us 

35 

Tyndis 

2 

Orontes 

33 

Typhon 

33 

Orosines 

29 

Ulysses 

33 

Oxus 

11 

Uranius 

8 

Pactolus 

11 

Xanthus 

12 

Padargus 

5 

The  number  of  canals  in  this  list  is  183,  and 
the  number  opposite  each  denotes  the  number 
of  times  each  was  seen  and  drawn  ;  (Sus.)  mean- 
ing, suspected  in  addition.  There  were  in  all, 
therefore,  3240  records  made  of  them,  not 
counting  suspicions. 


148  MARS 

In  the  region  visible  at  this  opposition  Schia- 
parelli  has  79  canals.  Of  these  67  appear  in  the 
list  given  above.  Of  the  other  12,  the  majority 
lie  north  of  the  equator,  and  therefore  were 
likely  not  to  be  as  visible  as  the  rest  at  this  last 
opposition,  for  two  reasons  connected  with  their 
position :  first,  on  account  of  the*  tilt  of  the 
planet's  axis  at  the  time ;  and,  secondly,  because 
their  northern  situation  would  make  their  de- 
velopment late,  as  we  shall  shortly  see.  As  no 
attempt  was  made  to  identify  Schiaparelli's  list, 
it  will  be  seen  how  close  is  the  accordance. 

Of  the  116  canals  not  down  on  Schiaparelli's 
map,  44  are  canals  in  the  dark  regions  and  72 
canals  in  the  light  ones.  Some  of  these,  too,  he 
saw  prior  to  1894.  Both  sets  are,  as  a  rule, 
more  difficult  of  detection  than  the  ones  on  his 
map ;  although  there  are  some  exceptions,  at- 
tributable probably  to  difficulty  of  identification. 
The  Brontes  and  Steropes,  for  example,  might, 
unless  well  seen,  be  confounded  with  the  Gigas 
on  the  one  hand,  or  the  Titan  on  the  other. 
The  most  peculiar  case,  however,  is  the  relative 
conspicuousness  of  the  Ulysses. 

III.   ARTIFICIALITY. 

It  is  patent  that  here  are  phenomena  that  are 
passing  strange.  To  read  their  riddle  we  had 
best  begin  by  excluding  what  they  are  not,  as 
help  towards  deciphering  what  they  are. 


ARTIFICIALITY  149 

So  far,  we  have  regarded  the  canals  only 
statically,  so  to  speak ;  that  is,  we  have  sketched 
them  as  they  would  appear  to  any  one  who  ob- 
served them  in  sufficiently  steady  air,  once,  and 
once  only.  But  this  is  far  from  all  that  a  sys- 
tematic study  of  the  lines  will  disclose.  Before, 
however,  entering  upon  this  second  phase  of 
their  description,  we  may  pause  to  note  how, 
even  statically  regarded,  the  aspect  of  the  lines 
is  enough  to  put  to  rest  all  the  theories  of 
purely  natural  causation  that  have  so  far  been 
advanced  to  account  for  them.  This  negation 
is  to  be  found  in  the  supernaturally  regular  ap- 
pearance of  the  system,  upon  three  distinct 
counts :  first,  the  straightness  of  the  lines ; 
second,  their  individually  uniform  width ;  and, 
third,  their  systematic  radiation  from  special 
points. 

On  the  first  two  counts  we  observe  that  the 
lines  exceed  in  regularity  any  ordinary  regu- 
larity of  purely  natural  contrivance.  Physical 
processes  never,  so  far  as  we  know,  end  in  pro- 
ducing perfectly  regular  results ;  that  is,  results 
in  which  irregularity  is  not  also  discernible. 
Disagreement  amid  conformity  is  the  inevitable 
outcome  of  the  many  factors  simultaneously  at 
work.  From  the  orbits  of  the  heavenly  bodies 
to  phyllotaxis  and  human  features,  this  diversity 
in  uniformity  is  apparent.  As  a  rule,  the  di- 
vergences, though  small,  are  quite  perceptible ; 


150  MARS 

that  is,  the  lack  of  absolute  uniformity  is  com- 
parable to  the  uniformity  itself,  and  not  of  the 
negligible  second  order  of  unimportance.  In 
fact,  it  is  by  the  very  presence  of  uniformity 
and  precision  that  we  suspect  things  of  artifi- 
ciality. It  was  the  mathematical  shape  of  the 
Ohio  mounds  that  suggested  mound-builders; 
and  so  with  the  thousand  objects  of  e very-day 
life.  Too  great  regularity  is  in  itself  the  most 
suspicious  of  circumstances  that  some  finite  in- 
telligence has  been  at  work. 

If  it  be  asked  how,  in  the  case  of  a  body  so 
far  off  as  Mars,  we  can  assert  sufficient  precision 
to  imply  artificiality,  the  answer  is  twofold  : 
first,  that  the  better  we  see  these  lines,  the 
more  regular  they  look ;  and,  second,  that  the 
eye  is  quicker  to  perceive  irregularity  than  we 
commonly  note.  It  is  indeed  surprising  to  find 
what  small  irregularities  will  shock  the  eye. 

The  third  count  is,  if  possible,  yet  more  con- 
clusive. That  the  lines  form  a  system ;  that, 
instead  of  running  any  whither,  they  join  cer- 
tain points  to  certain  others,  making  thus,  not  a 
simple  network,  but  one  whose  meshes  connect 
centres  directly  with  one  another,  —  is  striking 
at  first  sight,  and  loses  none  of  its  peculiarity 
on  second  thought.  For  the  intrinsic  improb- 
ability of  such  a  state  of  things  arising  from 
purely  natural  causes  becomes  evident  on  a 
moment's  consideration. 


ARTIFICIALITY  151 

If  lines  be  drawn  haphazard  over  the  sur- 
face of  a  globe,  the  chances  are  ever  so  many 
to  one  against  more  than  two  lines  crossing  each 
other  at  any  point.  Simple  crossings  of  two 
lines  will  of  course  be  common  in  proportion 
to  the  sum  of  an  arithmetical  progression ;  but 
that  any  three  lines  should  contrive  to  cross  at 
the  same  point  would  be  a  coincidence  whose  im- 
probability only  a  mathematician  can  properly 
appreciate,  so  very  great  is  it.  If  the  lines 
were  true  lines,  without  breadth,  the  chances 
against  such  a  coincidence  would  be  infinite, 
that  is,  it  would  never  happen ;  and,  even  had 
the  lines  some  breadth,  the  chances  would  be 
great  against  a  rendezvous.  In  other  words, 
we  might  search  in  vain  for  a  single  instance  of 
such  encounter.  On  the  surface  of  Mars,  how- 
ever, instead  of  searching  in  vain,  we  find  the 
thing  occurring  passim  ;  this  a  priori  most  im- 
probable rendezvousing  proving  the  rule,  not 
the  exception.  Of  the  crossings  that  are  best 
seen,  all  are  meeting-places  for  more  than  two 
canals. 

To  any  one  who  had  not  seen  the  canals,  it 
might  occur  that  something  of  the  same  improb- 
ability would  be  fulfilled  by  cracks  radiating 
from  centres  of  explosion  or  fissure.  But  such  a 
supposition  is  at  once  negatived  by  the  uniform 
breadth  of  the  lines,  a  uniformity  impossible  in 
cracks,  whose  very  mode  of  production  necessi- 


152  MARS 

tates  their  being  bigger  at  one  end  than  at  the 
other.  We  see  examples  of  what  might  result 
from  such  action  in  the  cracks  that  radiate  from 
Tycho,  in  the  Moon,  or,  as  we  now  know  from 
Professor  W.  H.  Pickering's  observations,  from 
the  craterlets  about  it.  These  cracks  bear  no 
resemblance  whatever  to  the  lines  on  Mars. 
They  look  like  cracks ;  the  lines  on  Mars 
do  not.  Indeed,  it  is  safe  to  say  that  the 
Martian  lines  would  never  so  much  as  suggest 
cracks  to  any  one.  Lastly,  the  different  radia- 
tions fit  into  one  another  absolutely,  an  utter 
impossibility  were  they  radiating  rifts  from  dif- 
ferent centres. 

In  the  same  way  we  may,  while  we  are  about 
it,  show  that  the  lines  cannot  be  several  other 
things  which  they  have  more  or  less  gratui- 
tously been  taken  to  be.  They  cannot,  for  ex- 
ample, be  rivers  ;  for  rivers  could  not  be  so  obli- 
gingly of  the  same  size  at  source  and  mouth,  nor 
would  they  run  from  preference  on  arcs  of  great 
circles.  To  do  so,  practically  invariably,  would 
imply  a  devotion  to  pure  mathematics  not  com- 
mon in  rivers.  They  may,  in  some  few  in- 
stances, be  rectified  rivers,  which  is  quite 
another  matter.  Glaciation  cracks  are  equally 
out  of  the  question,  —  first,  for  the  causes  above 
mentioned  touching  cracks  in  general;  and, 
second,  because  there  is,  unfortunately,  no  ice 
where  they  occur.  Nor  can  the  lines  be  fur- 


AKTIFICIALITY  153 

rows  ploughed  by  meteorites,  —  another  ingen- 
ious suggestion,  —  since,  in  order  to  plough, 
invariably,  a  furrow  straight  from  one  centre  to 
another,  without  either  missing  the  mark  or 
overshooting  it,  the  visitant  meteorite  would 
have  to  be  specially  trained  to  the  business. 

Such  are  the  chief  purely  natural  theories  of 
the  lines,  excluding  the  idea  of  canals,  —  the- 
ories advanced  by  persons  who  have  not  seen 
them.  No  one  who  has  seen  the  lines  well 
could  advance  them,  inasmuch  as  they  are  not 
only  disproved  by  consideration  of  the  char- 
acter of  the  lines,  but  instantly  confuted  by  the 
mere  look  of  them. 

Schiaparelli  supposes  the  canals  to  be  canals, 
but  of  geologic  construction.  He  suggests,  how- 
ever, no  explanation  of  how  this  is  possible ;  so 
that  the  suggestion  is  not,  properly  speaking, 
a  theory.  That  eminent  astronomer  further 
says  of  the  idea  that  they  are  the  work  of  intel- 
ligent beings :  "  lo  mi  guardero  bene  dal  com- 
battere  questa  supposizione,  la  quale  nulla 
include  d'  impossibile."  (I  should  carefully  re- 
frain from  combating  this  supposition,  which 
involves  no  impossibility.)  In  truth,  no  natural 
theory  has  yet  been  advanced  which  will  ex- 
plain these  lines. 

Their  very  aspect  is  such  as  to  defy  natural 
explanation,  and  to  hint  that  in  them  we  are 
regarding  something  other  than  the  outcome  of 


154  MARS 

purely  natural  causes.  Indeed,  such  is  the  first 
impression  upon  getting  a  good  view  of  them. 
How  instant  this  inference  is  becomes  patent 
from  the  way  in  which  drawings  of  the  canals 
are  received  by  incredulously  disposed  persons. 
The  straightness  of  the  lines  is  unhesitatingly 
attributed  to  the  draughtsman.  Now  this  is  a 
very  telling  point.  For  it  is  a  case  of  the 
double-edged  sword.  Accusation  of  design,  if 
it  prove  not  to  be  due  to  the  draughtsman, 
devolves  ipso  facto  upon  the  canals. 

IV.    DEVELOPMENT 

We  have  thus  far  considered  the  aspect  of 
the  canals  viewed  at  any  one  time.  We  have 
now  to  consider  an  even  more  interesting 
branch  of  the  subject,  their  consecutive  appear- 
ances. The  "  open  sesame  "  to  our  comprehen- 
sion of  the  physical  condition  of  Mars  lies  in 
systematic  study  of  the  appearances  the  planet's 
surface  presents  night  after  night  and  month 
after  month.  For  that  surface  changes;  and 
the  order,  extent,  and  character  of  its  changes 
contain  the  key  to  their  explanation.  True  as 
this  is  of  the  larger  markings  upon  the  disk,  it 
is  if  anything  more  noticeably  the  case  with  the 
finer  detail  of  the  canals. 

After  the  fundamental  fact  that  such  curious 
phenomena  as  the  canals  are  visible,  is  the 
scarcely  less  curious  one  that  they  are  not 


DEVELOPMENT  155 

always  so.  At  times  the  canals  are  invisible, 
and  this  invisibility  is  real,  not  apparent ;  that 
is,  it  is  not  an  invisibility  due  to  distance  or 
obscuration  of  any  kind  between  us  and  them, 
but  an  actual  invisibility  due  to  the  condition 
of  the  canal  itself.  With  our  present  optical 
means,  at  certain  seasons  they  cease  to  exist. 
For  aught  we  can  see,  they  simply  are  not 
there. 

That  distance  is  not  responsible  for  the  disap- 
pearance of  the  canals  is  shown  by  their  relative 
conspicuousness  at  different  times.  It  is  not 
always  when  Mars  is  nearest  to  us  that  the 
canals  are  best  seen.  On  the  contrary,  their 
visibility  bears  no  relation  to  proximity.  This 
is  evidenced  both  by  the  changes  in  appear- 
ance of  any  one  canal  and  by  the  changes 
in  relative  conspicuousness  of  different  canals. 
Some  instances  of  the  metamorphosis  will  re- 
veal this  conclusively.  For  example,  during 
the  end  of  August  and  the  beginning  of  Sep- 
tember, at  this  last  opposition,  the  canals  about 
the  Lake  of  the  Sun  were  conspicuous,  while 
the  canals  to  the  north  of  them  were  almost 
invisible.  In  November  the  relative  intensities 
of  the  two  sets  had  distinctly  changed :  the 
southern  canals  were  much  as  before,  but  the 
northern  ones  had  most  perceptibly  darkened. 

Another  instance  of  the  same  thing  was 
shown  in  the  case  of  the  canals  to  the  north  of 


156  MARS 

the  Sinus  Titanum  when  compared  with  those 
about  the  Solis  Lacus.  In  August  the  former 
were  but  faintly  visible ;  in  November  they  had 
become  evident ;  and  yet,  during  this  interval, 
little  change  in  conspicuousness  had  taken  place 
in  the  canals  in  the  Solis  Lacus  region. 

With  like  disregard  of  the  effect  due  to  dis- 
tance, the  canals  to  the  east  of  the  Ganges 
showed  better  at  the  November  presentation1  of 
that  region  than  they  had  at  the  October  one, 
although  the  planet  was  actually  farther  off  at 
the  later  date,  in  the  proportion  of  21  to  18. 

A  more  striking  instance  of  the  irrelevancy 
of  distance  in  the  matter  was  observed  in  the 
same  region  by  Schiaparelli  in  1877.  It  is  ad- 
ditionally interesting  as  practically  dating  his 
discovery  of  the  canals.  In  early  October  of 
that  year,  on  the  evenings  of  the  2d  and  the 
4th,  he  tells  us,  under  excellent  definition,  and 
with  the  diameter  of  the  planet's  disk  21"  of 
arc,  the  continental  region  between  the  Pearl- 
Bearing  Gulf  and  the  Bay  of  the  Dawn  was 
quite  uniformly,  nakedly  bright,  and  destitute 

1  A  presentation  of  any  part  of  the  planet  is  the  occasion 
•when  that  part  of  the  disk  is  turned  toward  the  observer.  Many 
causes  combine  to  make  the  face  presented  each  night  vary,  but 
the  chief  one  is  that  the  Earth  rotates  about  forty-one  minutes 
faster  than  Mars,  and  consequently  gains  a  little  less  than  ten  de- 
grees on  him  daily.  After  about  thirty-seven  days,  therefore, 
the  two  planets  again  present  the  same  face  to  each  other  at  the 
same  hour. 


DEVELOPMENT  157 

of  suspicion  of  markings  of  any  sort.  A  like 
state  of  things  was  the  case  with  the  same  re- 
gion at  its  next  presentation,  on  the  7th  of 
November.  Four  months  later,  when  the  di- 
ameter of  the  disk  had  been  reduced  by  dis- 
tance to  5". 7,  or,  in  other  words,  when  the 
planet  had  receded  to  four  times  its  previous 
distance  from  the  earth,  the  canal  called  the 
Indus  appeared,  perfectly  visible,  in  the  region 
mentioned.  At  the  next  opposition,  in  1881, 
similar  effects  occurred  ;  the  canals  in  this  re- 
gion remaining  obstinately  invisible  while  the 
planet  was  near  the  earth,  and  then  coming  out 
conspicuously  when  it  had  gone  farther  away. 
Distance,  therefore,  is  not,  with  the  canals,  the 
great  obliterator. 

As  to  their  veiling  by  Martian  cloud  or  mist, 
there  is  no  evidence  of  any  such  obscuration. 
The  coast  line  of  the  dark  areas  appears  as 
clear-cut  when  the  canals  are  invisible  as  when 
they  become  conspicuous. 

A  canal,  then,  alters  in  visibility  for  some 
reason  connected  with  itself.  It  grows  into 
recognition  from  intrinsic  cause.  But,  during 
all  its  metamorphoses,  in  one  thing,  and  in  one 
thing  only,  it  remains  fixed,  —  in  position. 
Temporary  in  appearance,  the  canals  are  appar- 
ently permanent  in  place.  Not  only  do  they 
not  change  in  position  during  one  opposition ; 
they  seem  not  to  do  so  from  one  opposition  to 


158  MARS 

another.  The  canals  I  have  observed  this  year 
agree  fairly  within  the  errors  of  observation 
with  those  figured  on  Schiaparelli's  chart. 

The  fact  that  in  all  cases  they  do  not  abso- 
lutely agree  with  his  is  the  very  best  of  proofs 
that  they  are  substantially  the  same  ;  for  such 
slight  discordance  proves  the  absence  of  con- 
scious psychic  reproduction.  It  confirms  by 
not  conforming. 

As,  in  observations  of  minute  detail,  the 
psychic  element  insensibly  creeps  in,  it  will  be 
well  to  consider  it  for  a  moment.  An  idea  is 
a  force,  a  mode  of  motion,  which,  unless  ob- 
structed by  other  ideas,  instantly  and  inevitably 
produces  its  effect  upon  whatever  mind  it  may 
chance  to  impinge,  just  as  light  or  electricity  or 
any  other  mode  of  motion  does,  according  to  its 
kind.  An  easy  instance  of  this  can  be  got  by 
asserting  at  dinner,  before  a  company  of  con- 
noisseurs, that  the  wine  is  slightly  corked. 
Every  one  not  actuated  by  a  spirit  of  contradic- 
tion will  at  once  perceive  that  it  is  so,  and  will 
continue  to  believe  it,  in  many  cases,  after  it  is 
abundantly  disproved.  This  is  what  takes  place 
in  the  normal,  unbiased  —  that  is,  so  far  as  this 
idea  goes — vacant  mind.  But  minds  have  their 
familiar  ideas,  which  an  incoming  idea  is  pretty 
sure  to  rouse,  and  these  react  to  some  extent 
upon  the  stranger,  and  color  it  with  something 
of  their  own  complexion.  If  we  expect  to  meet 


DEVELOPMENT  159 

a  certain  person,  an  approaching  figure  will 
most  deceitfully  take  on  his  garb.  The  mere 
idea  of  a  man  walking  finds  the  expectation 
ready  instinctively  to  endow  it  with  the  attri- 
butes of  our  friend.  But  this  may  happen 
truly  as  well  as  falsely.  The  expert  sees  what 
the  tyro  misses,  not  from  better  eyesight  but 
from  better  mechanism  in  the  higher  centres. 
A  very  slight  hint  from  the  eye  goes  a  long 
way  in  the  brain  of  the  one  ;  no  distance  at  all 
in  the  brain  of  the  other. 

Our  senses  are  our  avenues  of  approach  from 
the  outer  world.  Messages  from  them  are 
therefore  usually  and  rightly  attributed  to 
stimuli  from  without.  But  it  is  possible  for 
these  messages  to  be  tampered  with  at  any 
stage  of  their  journey.  It  is  even  possible  for 
them  to  be  started  in  some  other  part  of  the 
brain,  travel  down  to  the  lower  centres  and  be 
sent  up  from  them  to  the  higher  ones,  indistin- 
guishable from  bona  fide  messages  from  with- 
out. Bright  points  in  the  sky  or  a  blow  on  the 
head  will  equally  cause  one  to  see  stars.  In  the 
first  case  the  eyes  were  duly  affected  from 
without ;  in  the  second,  the  nerves  were  tapped 
to  the  same  effect  in  mid-route  ;  but  in  each 
case  the  subsequent  current  travels  to  the 
higher  centres  apparently  as  authentic  the  one 
as  the  other. 

Hallucinations  of  one  sort  and  another  occur 


160  MARS 

in  this  way.  More  common,  however,  are  un- 
conscious changes  in  an  originally  quite  veridic 
message.  We  easily  see  what  we  expect  to  see, 
but  with  great  difficulty  what  we  do  not.  This 
may  be  due  to  individual  idiosyncrasy,  or  it  may 
be  due  to  a  prevailing  idea  of  the  time,  affecting 
people  generally,  in  which  we  unwittingly  share. 
Fashion  is  as  potent  here  as  elsewhere.  The 
very  same  cause  will  show  us  at  one  time  what 
we  remain  callously  blind  to  at  another.  A 
few  years  ago  it  was  the  fashion  not  to  see  the 
canals  of  Mars,  and  nobody  except  Schiaparelli 
did.  Now  the  fashion  has  begun  to  set  the 
other  way,  and  we  are  beginning  to  have  pre- 
sented suspiciously  accurate  fac-similes  of  Schia- 
parelli's  observations. 

In  any  observation,  the  observer  is  likely  to 
be  unconsciously  affected  in  some  way  or  other 
pro  or  con,  which,  from  the  fact  that  he  is  un- 
conscious of  it,  he  is  unable  to  find  out.  The 
only  sure  test,  therefore,  is  the  seeing  what  no 
one  else  has  seen,  the  discovery  of  new  detail. 
Next  to  that  is  not  too  close  an  agreement  with 
others.  Inevitable  errors  of  observation,  to  say 
nothing  of  times  and  seasons,  distance  and  tilt, 
are  certain  to  produce  differences,  of  which  one 
has  ample  proof  in  comparing  his  own  drawings 
with  one  another.  Even  too  close  agreement 
with  one's  self  is  suspicious.  In  the  matter 
of  fine  detail,  absolute  agreement  is  therefore 
neither  to  be  expected  nor  to  be  desired. 


DEVELOPMENT  161 

All  the  changes  so  far  observed  on  the 
planet's  disk  are,  I  believe,  capable  of  explana- 
tion either  by  errors  of  observation  or  by  sea- 
sonal change.  For,  as  is  the  case  with  the 
Earth,  not  only  must  vegetation  produce  differ- 
ent appearances  according  to  the  time  of  year, 
but  its  aspects  would  vary  somewhat  as  between 
year  and  year.  This  seasonal  variation  would 
affect  not  only  the  visibility  of  any  one  canal  at 
any  particular  time,  but  might  easily  produce 
apparent  alterations  of  place ;  visibility  of  one 
canal,  combined  with  visibility  or  invisibility  in 
its  neighbors,  being  competent  to  simulate  any 
shift. 

The  Araxes  is  a  case  in  point.  On  Schiapa- 
relli's  chart  there  is  but  one  original  Araxes 
and  one  great  and  only  Phasis.  But  it  turns 
out  that  these  do  not  possess  the  land  all  to 
themselves.  No  less  than  five  canals  traversing 
the  region,  including  the  Phasis  itself,  were  vis- 
ible this  year  at  Flagstaff,  and  I  have  no  doubt 
there  are  plenty  of  others  waiting  to  be  dis- 
covered. These  cross  one  another,  at  all  sorts 
of  angles.  Unconscious  combination  of  them  is 
quite  competent  to  give  a  turn  to  the  Araxes 
one  way  or  the  other,  and  make  it  curved  or 
straight  at  pleasure. 

Unchangeable,  apparently,  in  position,  the 
canals  are  otherwise  among  the  most  change- 
able features  of  the  Martian  disk.  From  being 


162  MARS 

invisible,  they  emerge  gradually,  for  some  rea- 
son inherent  in  themselves,  into  conspicuous- 
ness.  In  short,  phenomenally  at  least,  they 
grow.  The  order  of  their  coming  carries  with 
it  a  presumption  of  cause,  for  it  synchronizes 
with  the  change  in  the  Martian  seasons.  Their 
first  appearance  is  a  matter  of  the  Martian  time 
of  year. 

To  start  with,  the  visible  development  of  the 
canal  system  follows  the  melting  of  the  polar 
snows.  Not  until  such  melting  has  progressed 
pretty  far  do  any  of  the  canals,  it  would  seem, 
become  perceptible. 

Secondly,  when  they  do  appear,  it  is,  in  the 
case  of  the  southern  hemisphere,  the  most 
southern  ones  that  become  visible  first.  Last 
June,  when  the  canals  were  first  seen,  those 
about  the  Lake  of  the  Sun  and  the  Phoenix 
Lake  were  easier  to  make  out  than  any  of  the 
others.  Now,  this  region  is  the  part  of  the 
reddish-ochre  continent,  as  we  may  call  it,  that 
lies  nearest  the  south  pole.  It  extends  into 
the  blue-green  regions  as  far  south  as  40°  of 
south  latitude.  Nor  do  any  so-called  islands  — 
that  is,  smaller  reddish-ochre  areas  —  stand  be- 
tween it  and  the  pole.  It  lies  first  exposed, 
therefore,  to  any  water  descending  toward  the 
equator  from  the  melting  of  the  polar  cap. 

Having  once  become  visible,  these  canals  re- 
mained so,  becoming  more  and  more  conspicu- 


PLATE  XIX 


LACUS   PHOENICIS 
NOVEMBER,  1894 


DEVELOPMENT  163 

cms  as  the  season  advanced.  By  August  they 
had  darkened  very  perceptibly.  As  yet,  those 
in  other  parts  of  the  planet  were  scarcely  more 
visible  than  they  had  been  two  months  before. 
Gradually,  however,  others  became  evident,  far- 
ther and  farther  north,  till  by  October  all  the 
canals  bordering  the  north  coast  of  the  dark 
regions  were  recognizable ;  after  which  the  lat- 
ter, in  their  turn,  proceeded  to  darken,  —  a  state 
of  things  which  continued  up  to  the  close  of 
observations.  (Plates  XXI.  and  XXII.) 

The  order  in  which  the  canals  came  out 
hinted  that  two  factors  were  operative  to  the 
result,  —  latitude  and  proximity  to  the  dark  re- 
gions. Other  things  equal,  the  most  southern 
ones  showed  first;  beginning  with  the  Solis 
Lacus  region,  and  continuing  with  those  about 
the  Sea  of  the  Sirens  and  the  Titan  Gulf,  and 
so  northward  down  the  disk.  Other  things  were 
not,  however,  always  equal  in  the  way  of  topo- 
graphical position.  Notably  was  this  the  case 
with  the  areas  to  the  west  of  the  Syrtis  Major, 
which  developed  canals  earlier  than  their  lati- 
tudes would  warrant.  Now,  to  the  Syrtis  Major 
descend  from  the  pole  the  great  straits  spoken 
of  before,  which,  although  not  in  their  entirety 
water,  are  probably  lands  fertilized  by  a  thread 
of  water  running  through  them.  They  connect 
the  polar  sea  with  the  Syrtis  Major  in  a  toler- 
ably straight  line. 


164  MARS 

The  direction  of  the  canal  also  affects  its  time 
of  appearance,  though  to  a  less  extent.  Canals 
running  north  and  south,  such  as  the  Gorgon, 
the  Titan,  the  Brontes,  and  the  like,  became 
visible,  as  a  rule,  before  those  running  east 
and  west.  Especially  was  this  noticeable  in  the 
more  northern  portions  of  the  disk.  Time  of 
appearance  was  evidently  a  question  of  latitude 
tempered  by  ease  of  communication. 

After  the  canals  had  appeared,  their  relative 
intensities  changed  with  time,  and  the  change 
followed  the  same  order  in  which  the  initial 
change  from  invisibility  to  visibility  had  taken 
place.  A  like  metamorphosis  happened  to  each 
in  turn  from  south  to  north,  in  accordance  with, 
and  continuance  of,  the  seasonal  change  that 
affected  all  the  blue-green  areas. 

To  account  for  these  phenomena,  the  expla- 
nation that  at  once  suggests  itself  is,  that  a 
direct  transference  of  water  takes  place  over 
the  face  of  the  planet,  and  that  the  canals  are 
so  many  waterways.  This  explanation  labors 
under  the  difficulty  of  explaining  nothing. 
There  are  two  other  objections  to  it :  an  insuf- 
ficiency of  water,  and  a  superabundance  of  time, 
for  some  months  elapsed  between  the  apparent 
departure  of  the  water  from  the  pole  and  its 
apparent  advent  in  the  equatorial  regions ;  fur- 
thermore, each  canal  did  not  darken  all  at  once, 
but  gradually.  We  must  therefore  seek  some 


DEVELOPMENT  165 

explanation  which  accounts  for  this  delay.  Now, 
when  we  do  so,  we  find  that  the  explanation  ad- 
vanced above  for  the  blue-green  areas  explains 
also  the  canals,  namely,  that  what  we  see  in  both 
is,  not  water,  but  vegetation;  for  if  the  dark- 
ening be  due  to  vegetation,  time  must  elapse 
between  the  advent  of  the  water  and  its  per- 
ceptible effects,  —  time  sufficient  for  the  flora  to 
sprout.  If,  therefore,  we  suppose  what  we  call 
a  canal  to  be,  not  the  canal  proper,  but  the 
vegetation  along  its  banks,  the  observed  phe- 
nomena stand  accounted  for.  This  suggestion 
was  first  made  some  years  ago  by  Professor  W. 
H.  Pickering. 

That  what  we  see  is  not  the  canal  proper,  but 
the  line  of  land  it  irrigates,  disposes  incidentally 
of  the  difficulty  of  conceiving  a  canal  several 
miles  wide.  On  the  other  hand,  a  narrow,  fer- 
tilized strip  of  country  is  what  we  should  expect 
to  find ;  for,  as  we  have  seen,  the  general  phys- 
ical condition  of  the  planet  leads  us  to  the  con- 
ception, not  of  canals  constructed  for  waterways, 
—  like  our  Suez  Canal,  —  but  of  canals  dug  for 
irrigation  purposes.  We  cannot,  of  course,  be 
sure  that  such  is  their  character,  appearances 
being  often  highly  deceitful ;  we  can  only  say 
that,  so  far,  the  supposition  best  explains  what 
we  see.  Further  details  of  their  development 
point  to  this  same  conclusion. 

In  emerging  from  invisibility  into  evidence, 


166  MARS 

the  canals  first  make  themselves  suspected, 
rather  than  seen,  as  broad,  faint  streaks  smooch- 
ing the  disk.  Such  effect,  however,  seems  to  be 
an  optical  illusion,  due  to  poor  air  and  the  diffi- 
culty inherent  in  detecting  fine  detail ;  for  on 
improvement  in  the  seeing  I  have  observed 
these  broad  streaks  contract  to  fine  lines,  not 
sensibly  different  in  width  from  what  they 
eventually  become. 

The  parts  of  the  canals  which  are  nearest  the 
dark  areas  show  first,  the  line  extending  some- 
times for  a  few  hundred  miles  into  the  conti- 
nent, sometimes  for  a  thousand  or  more ;  then, 
in  course  of  time,  the  canal  becomes  evident 
in  its  entirety.  Complete  visibility  takes  place 
soon  after  the  canal  has  once  begun  to  show, 
although  it  show  but  faintly  throughout. 

This  tendency  to  being  seen  in  toto  is  more 
strikingly  displayed  after  a  canal  has  attained 
its  development.  It  is  then  not  commonly  seen 
in  part.  Either  it  is  not  seen  at  all,  owing  to 
the  seeing  not  being  good  enough,  or  it  is  visi- 
ble throughout  its  length  from  one  junction  to 
another. 

Apart  from  their  extension,  the  growth  of  the 
canals  consists  chiefly  in  depth  of  tint.  They 
darken  rather  than  broaden,  —  a  fact  which 
tends  to  corroborate  their  vegetal  character; 
for  that  long  tracts  of  country  should  be  thus 
simultaneously  flooded  all  over  to  a  gradually 


DEVELOPMENT  167 

deepening  extent  is  highly  unlikely,  while  a 
growth  of  vegetation  would  deepen  in  appear- 
ance in  precisely  the  way  in  which  the  darken- 
ing takes  place. 

As  for  color,  the  lines  would  seem  to  be  of 
the  same  tint  as  the  blue-green  areas.  But, 
owing  to  their  narrowness,  this  is  only  an  infer- 
ence. I  have  never  chanced  to  see  them  of 
distinctive  color. 

At  this  point  it  is  probable  that  a  certain  ob- 
stacle to  such  wholesale  construction  of  canals, 
however,  will  arise  in  the  mind  of  the  reader, 
namely,  the  thought  of  mountains ;  for  moun- 
tains are  by  nature  antagonistic  to  canals.  Only 
the  Czar  of  all  the  Russias  —  if  we  are  to  credit 
the  account  of  the  building  of  the  Moscow  rail- 
way—  would  be  capable  of  running  a  canal  re- 
gardless of  topography.  Nor  will  the  doings 
at  our  own  antipodes  help  us  to  conceive  such 
construction ;  for  though  the  Japanese  irrigate 
hillsides,  the  water  in  the  case  comes  from  slopes 
higher  yet,  whereas  on  Mars  it  does  not. 

Indeed,  for  the  lines  to  contain  canals  we 
must  suppose  either  that  mountains  prove  no 
obstacles  to  the  Martians,  or  else  that  there 
are  practically  no  mountains  on  Mars.  For  the 
system  seems  sublimely  superior  to  possible  ob- 
structions in  the  way ;  the  lines  running,  appar- 
ently, not  where  they  may,  but  where  they 
choose.  The  Eumenides-Orcus,  for  example, 


168  MARS 

pursues  the  even  tenor  of  its  unswerving  course 
for  nearly  3500  miles.  Now,  it  might  be  pos- 
sible so  to  select  one's  country  that  one  canal 
should  be  able  to  do  this;  but  that  every 
canal  should  be  straight,  and  many  of  them 
fairly  comparable  with  the  Eumenides-Orcus  in 
length,  seems  to  be  beyond  the  possibility  of 
contrivance. 

In  this  dilemma  between  mountains  on  the 
one  hand  and  canals  on  the  other,  a  certain 
class  of  observations  most  opportunely  comes  to 
our  aid ;  for,  from  observations  which  have 
nothing  to  do  with  the  lines,  it  turns  out 
that  the  surface  of  the  planet  is,  in  truth,  most 
surprisingly  flat.  How  this  is  known  will  most 
easily  be  understood  from  a  word  or  two  upon 
the  manner  in  which  astronomers  have  learnt 
the  height  of  the  mountains  in  the  Moon. 

The  heights  of  the  lunar  mountains  are  found 
from  measuring  the  lengths  of  the  shadows  they 
cast.  As  the  Moon  makes  her  circuit  of  the 
Earth,  a  varying  amount  of  her  illuminated  sur- 
face is  presented  to  our  view.  From  a  slender 
sickle  she  grows  to  full  moon,  and  then  dimin- 
ishes again  to  a  crescent.  The  illuminated  por- 
tion is  bounded  by  a  semicircle  on  the  one  side, 
and  by  a  semi-ellipse  on  the  other.  The  semi- 
circle is  called  her  limb,  the  semi-ellipse  her 
terminator.  The  former  is  the  edge  we  see  be- 
cause we  can  see  no  farther ;  the  latter,  the 


DEVELOPMENT  169 

line  upon  her  surface  where  the  sun  is  just  ris- 
ing or  setting.  Now,  as  we  know,  the  shadows 
cast  at  sunrise  or  sunset  are  very  long,  much 
longer  than  the  objects  that  cast  them  are  high. 
This  is  due  to  the  obliquity  at  which  the  light 
strikes  them ;  the  same  effect  being  produced 
by  any  sufficiently  oblique  light,  such  as  an 
electric  light  at  a  distance.  Imperceptible  in 
themselves,  the  heights  become  perceptible  by 
their  shadows.  A  road  illuminated  by  a  distant 
arc  light  gives  us  a  startling  instance  of  this; 
the  smooth  surface  taking  on  from  its  shadows 
the  look  of  a  ploughed  field. 

It  is  this  indirect  kind  of  magnification  that 
enables  astronomers  to  measure  the  lunar  moun- 
tains, and  even  renders  such  vicariously  visible 
to  the  naked  eye.  Every  one  has  noticed  how 
ragged  and  irregular  the  inner  edge  of  the  Moon 
looks,  while  her  outer  edge  seems  perfectly 
smooth.  In  one  place  it  will  appear  to  project 
beyond  the  perfect  ellipse,  in  another  to  recede 
from  it.  The  first  effect  is  due  to  mountain  tops 
catching  the  sun's  rays  before  the  plains  about 
them ;  the  other,  to  mountain  tops  further  ad- 
vanced into  the  lunar  day,  whose  shadows  still 
shroud  the  valleys  at  their  feet.  Yet  the  ele- 
vations and  depressions  thus  rendered  so  notice- 
able vanish  in  profile  on  the  limb. 

Much  as  we  see  the  Moon  with  the  naked  eye 
do  we  see  Mars  with  the  telescope.  Mars  being 


170  MARS 

outside  of  us  with  regard  to  the  Sun,  we  never 
see  him  less  than  half  illumined,  but  we  do  see 
him  with  a  disk  that  lacks  of  being  round,  — 
about  what  the  Moon  shows  us  when  two  days 
off  from  full.  It  is  when  he  is  in  quadrature  — 
that  is,  a  quarter  way  round  the  celestial  circle 
from  the  Sun  —  that  he  shows  thus,  and  wre 
see  him  then  with  the  telescope  at  closer  range 
than  we  ever  see  the  Moon  without  it.  So  ob- 
served we  notice  at  once  that  his  terminator,  or 
inner  edge,  presents  a  very  different  appearance 
from  the  lunar  one.  Instead  of  looking  like  a 
saw,  it  looks  comparatively  smooth,  like  a  knife. 
From  this  we  know  that,  relatively  to  his  size, 
he  has  no  elevations  or  depressions  upon  his  sur- 
face comparable  to  the  lunar  peaks  and  craters. 
His  terminator,  however,  is  not  absolutely 
perfect.  Irregularities  are  to  be  detected  in  it, 
although  much  less  pronounced  than  those  of 
the  Moon.  His  irregularities  are  of  two  kinds. 
The  first,  and  by  all  odds  the  commonest  pheno- 
menon, consists  in  showing  himself  on  occasions 
surprisingly  flat ;  not  in  this  case  an  inferable 
flatness,  but  a  perfectly  apparent  one.  In  other 
words,  his  terminator  does  not  show  as  a  semi- 
ellipse,  but  as  an  irregular  polygon.  It  looks 
as  if  in  places  the  rind  had  been  pared  off.  The 
peel  thus  taken  from  him,  so  to  speak,  is  from 
twenty  to  forty  degrees  wide,  according  to  the 
particular  part  of  his  surface  that  shows  upon 
the  terminator  at  the  time. 


PLATE  XX 


TERMINATOR  VIEWS 

BY  PROF.  W.  H.  PICKERING 

August  24,  1894 

A  scries  of  unusually  marked  elevations  and  degressions  upon  the 
terminator  at  the  above  hours 


PLATE  XXI 


FIG.  I.     Nov.  26.    Long.  cent.  314° 
Seeing  2  to  6.    Diam.  is".8 


FIG.  II.     Oct.  9.     Long.  cent.  45° 
Seeing  5  to  9.    Diam.  21".  7 


FIG.  III.     Feb.  8.     Long.  cent.  295° 
Seeing  2  to  5.     Diam.  7".$ 


FIG.  IV.     Nov.  23.     Long.  cent.  31° 
Seeing  2  to  7.    Diam.  i6".3 


FIG.  V.     March  16.     Long.  cent.  312° 
Seeing  2  to  8.    Diam.  6^.4 


FIG.  VI.     March  9.     Long.  cent.  26° 
Seeing  3  to  7.    Diam.  6" .6 


DRAWINGS  AFTER  OPPOSITION  [EXCEPT  ONE] 
By  A.  E.  DOUGLASS 


DEVELOPMENT  171 

The  other  kind  is  short  and  sharp.  Now  it 
will  be  remembered  that  we  considered  both 
kinds  under  the  question  of  atmosphere,  and  we 
found  both  to  be  explicable  as  the  effect  of 
clouds,  but  not  the  effect  of  mountains  We 
may  therefore  feel  tolerably  certain  that  Mars 
is  a  flat  world  ;  devoid,  as  we  may  note  inciden- 
tally, of  summer  resorts,  since  it  possesses,  ap- 
parently, neither  seas  nor  hills.  To  canals  we 
will  now  return. 

The  canals  so  far  described  all  lie  in  the 
bright  reddish-ochre  portions  of  the  disk, — 
those  parts  which  bear  every  appearance  of 
being  desert.  But  Mr.  Douglass  has  made  the 
discovery  that  they  are  not  the  only  part  of  the 
planet  thus  privileged.  He  finds,  in  the  very 
midst  of  the  dark  regions  themselves,  straight, 
dark  streaks  not  unlike  in  look  to  the  canals, 
and  still  more  resembling  them  in  the  systematic 
manner  in  which  they  run.  For  they  reproduce 
the  same  rectilinear  arrangement  that  is  so 
striking  a  characteristic  of  their  bright-area 
fellows.  He  has  succeeded,  indeed,  in  thus  tri- 
angulating all  the  more  important  dark  areas. 

Now  this  is  a  very  interesting  discovery,  from 
several  points  of  view.  In  the  first  place,  it 
proves  another  tell-tale  circumstance  as  to  the 
true  character  of  the  so-called  seas ;  for  that  the 
seas  should  be  traversed  by  permanent  dark  lines 
is  incompatible  with  a  fluid  constitution.  But 


172  MARS 

the  lines  are  even  more  suggestive  from  a  posi- 
tive than  they  are  from  a  negative  standpoint. 
For  they  make  continuations  of  the  lines  in  the 
bright  regions,  showing  that  the  two  are  caus- 
ally connected,  and  affording  strong  presump- 
tion that  this  causal  relation  is  the  very  one  de- 
manded by  the  theory  of  irrigation.  For  if  the 
canals  in  the  bright  regions  be  strips  of  vegeta- 
tion irrigated  by  a  canal  (too  narrow  to  be  itself 
visible  at  our  distance),  and  there  be  a  scarcity 
of  water  upon  the  surface  of  the  planet,  the 
necessary  water  would  have  to  be  conducted  to 
the  mouths  of  the  canals  across  the  more  per- 
manent areas  of  vegetation,  thus  causing  bands 
of  denser  verdure  athwart  them,  which  we 
should  see  as  dark  lines  upon  the  less  dark 
background.  Indeed,  it  is  exactly  what  we 
should  expect  to  find  if  the  theory  here  ad- 
vanced be  true.  For  it  is  the  very  next  logical 
step  in  that  theory  made  visible.  If  the  canals 
in  the  bright  regions  are  to  be  fed  from  the 
melting  of  the  polar  cap,  it  is  altogether  likely 
that  they  would  be  connected  with  it  by  other 
canals  running  through  the  dark  regions.  We 
might,  therefore,  expect  to  see  lines  in  the  dark 
regions  not  unlike  the  lines  in  the  bright  ones, 
and  if  these  lines  were  of  the  same  character  as 
those  in  the  bright  regions  they  would  betray 
this  character  by  connecting  directly  with  them. 
Now  this  is  precisely  what  he  finds  the  two  sets 


PLATE  XXII 


FIG.  I.     Nov.  14.     Long.  cent.  114°  FIG.  II.     Nov.  5.     Long.  cent.  184° 

Seeing  4  to  8.     Diam.  iy".9  Seeing  i  to  3.     Diam.  19".$ 

an 

FIG.  III.     Dec.  17.     Long.  cent.  100°  FIG.  IV.     Dec.  i.     Long.  cent.  246° 

Seeing  2  to  6.     Diam.  12". 4  Seeing  2  to  4.     Diam.  14". 9 


FIG.  VI.     Jan.  8.     Long.  cent.  266° 
Seeing  2  to  4.     Diam.  7".4  Seeing  i  to  3.     Diam.  g".9 

DRAWINGS   AFTER   OPPOSITION 
BY  A.  E.  DOUGLASS 


DEVELOPMENT 


173 


of  lines  do.  His  canals  in  the  dark  regions  end 
at  the  very  points  at  which  the  others  begin, 
and  they  do  this  invariably.  There  is  no  canal 
in  the  dark  areas  which  does  not  so  connect 
with  one  in  the  bright  regions. 

Finally,  some  of  the  most  southern  appear  to 
run  tolerably  straight  toward  the  pole ;  but  of 
the  plan  underlying  the  whole  system  of  Martian 
canals  we  cannot  at  present  predicate  details, 
as,  though  the  system  instantly  suggests  plan,  it 
suggests  a  plan  that  does  not  instantly  commend 
itself  to  human  comprehension. 

Mr.  Douglass  finds  44  of  these  canals,  not 
including  the  straits  between  the  islands,  as  is 
shown  in  the  following  list :  — 


Name. 

No.  of  drawings  in 
which  it  appears. 

Name. 

No.  of  drawings  in 
which  it  appears. 

Acalandrus 

19 

Dosaron 

10 

Acesines 

19 

Drahonus 

5 

Acis 

14 

Erannoboas 

17 

Aeolus 

13 

Erymanthus 

21 

Amphrysus 

1 

Eurypus 

9 

Athesis 

16 

Gaesus 

2 

Caicus 

8 

Galaesus 

6 

Carpis 

3 

Garrhuenus 

12 

Casuentus 

21 

Harpasus 

2 

Cayster 

3 

Helisson 

12 

Oestrus 

2 

Heratemis 

4 

Chaboras 

4 

Hipparis 

19 

Cinyphus 

14 

Hippus 

13 

Cyaneus 

6 

Hyctanis 

4 

Cyrus 

3 

Hydriacus 

1 

Dargamanes 

20 

Hylias 

7 

Digentia 

2 

Hyllus 

14 

174  MARS 


No.  of  drawings  in 
which  it  appears. 

Leontes  2 

Malva  8 

Mogrus  2 

Nestus  5 

Neudrus  10 


No.  of  drawings  in 
which  it  appears. 

Oceanus  37 

Opharus  13 

Orosines  29 

Padargus  5 

Tedanius  25 


All  these  run  either  through  the  dark  regions 
proper,  or  through  those  chiaro-oscuro  areas, 
such  as  Deucalionis  Regio  and  Pyrrhae  Regio, 
which  have  hitherto  been  thought  to  be  amphi- 
bious, and  are  probably  half  desert.  They  con- 
nect on  the  one  hand  with  the  canals  in  the 
bright  regions,  and  on  the  other  with  the  straits 
between  the  so-called  islands,  —  such  strait- 
canals  as  Scaraander,  Xanthus,  and  the  like,  if 
we  may  so  designate  without  misunderstanding 
what  is  probably  not  water  at  all. 

It  is  interesting  thus  to  forestall  objection 
about  a  missing  link  by  discovering  that  link 
thus  early. 

Before  passing  on  to  certain  other  pheno- 
mena connected  with  the  canals  of  like  signifi- 
cance, we  may  note  here  an  obiter  dictum  of  the 
irrigation  theory  of  some  slight  corroborative 
worth;  for,  if  a  theory  be  correct,  it  will  not 
only  fit  all  the  facts,  but  at  times  go  out  of  its 
way  to  answer  questions.  Such  the  present 
one  seems  to  do.  If  the  seas  be  seas,  and  the 
canals  canals,  we  stand  confronted  by  the  prob- 
lem how  to  make  fresh-water  canals  flow  out  of 


DEVELOPMENT  175 

salt-water  seas.  General  considerations  warrant 
us  in  believing  that  the  Martian  seas,  like  our 
own,  would  contain  salts  in  solution,  while  irri- 
gation ditches,  there  as  here,  should  flow  fresh 
water  to  be  most  effective,  and  we  seem  com- 
mitted to  the  erection  of  distilleries  upon  a 
gigantic  scale.  But  if,  on  the  contrary,  the 
seas  be  not  seas,  but  areas  of  vegetation,  the 
difficulty  vanishes  at  once ;  for,  if  the  planet  be 
dependent  upon  the  melting  of  its  polar  snows 
for  its  spring  freshet,  the  water  thus  produced 
must  necessarily  be  fresh,  and  the  canals  be 
directly  provided  with  the  water  they  want. 
The  polar  sea  is  a  temporary  body  of  water, 
formed  anew  each  year,  not  a  permanent  ocean ; 
consequently  there  is  no  chance  for  saline  mat- 
ter to  collect  in  it.  From  it,  therefore,  fresh 
water  flows,  and,  like  our  rivers,  gathers  nothing 
to  speak  of  in  the  way  of  salt  before  it  is  drawn 
off  into  the  canals. 

We  now  come  to  some  phenomena  connected 
with  the  canals,  of  the  utmost  suggestiveness. 
I  have  said  that  the  junctions  held,  in  a  twofold 
way,  the  key  to  the  unlocking  of  the  mystery 
of  the  canals  :  in  the  first  place,  in  the  fact  that 
such  junctions  exist.  The  second  and  more  im- 
portant reason  remains  to  be  given,  for  it  con- 
sists in  what  we  find  at  those  junctions.  This 
we  shall  see  in  the  next  chapter. 


V 

OASES 

I.    SPOTS   IN   THE   LIGHT   KEGIONS 

SUGGESTIVE  of  irrigation  as  the  strange  net- 
work of  lines  that  covers  the  surface  of  Mars 
appears  to  be,  the  suggestion  takes  on  more 
definite  shape  yet  with  the  last  addition  to  our 
knowledge  of  the  planet's  surface  detail,  —  the 
recognition  of  a  singularly  correlated  system  of 
spots. 

The  canals,  as  we  have  seen,  are  very  re- 
markably attached  to  one  another.  Indeed,  the 
manner  with  which  they  manage  to  combine 
undeviating  direction  with  meetings  by  the  way 
grows  more  and  more  marvelous,  the  more  one 
studies  it.  The  meeting-places,  or  junctions, 
are  evidently  for  something  in  the  constitution 
of  the  canals.  The  crossings,  in  fact,  seem  to 
be  the  end  and  aim  of  the  whole  system ;  the 
canals,  but  means  to  that  end.  So  much  is  at 
once  inferable  from  the  great  intrinsic  improba- 
bility that  such  crossings  can  be  due  to  chance. 

This  inference  receives,  apparently,  striking 
corroboration  when  the  planet  is  more  minutely 


SPOTS  IN  THE  LIGHT  REGIONS  177 

scanned.  For  there  turns  out  to  be  something 
at  these  junctions.  This  something  shows  itself 
as  a  round  or  oval  spot.  To  such  spot,  planted 
there  in  the  midst  of  the  desert  at  the  junction, 
do  the  neighboring  canals  converge. 

Dotted  all  over  the  reddish-ochre  ground  of 
the  desert  stretches  of  the  planet,  the  so-called 
continents  of  Mars,  are  an  innumerable  number 
of  dark  circular  or  oval  spots.  They  appear, 
furthermore,  always  in  intimate  association  with 
the  canals.  They  constitute  so  many  hubs  to 
which  the  canals  make  spokes.  These  spots, 
together  with  the  canals  that  lead  to  them,  are 
the  only  markings  to  be  seen  anywhere  on  the 
continental  regions.  Otherwise  the  great  red- 
dish-ochre areas  are  absolutely  bare  ;  of  that 
pale  fire-opal  hue  which  marks  our  own  deserts 
seen  from  far. 

That  these  two  things,  —  straight  lines  and 
roundish  spots,  —  should,  with  our  present  tele- 
scopic means,  be  the  sole  markings  to  appear 
on  the  vast  desert  regions  of  the  planet  is  sug- 
gestive in  itself. 

Another  significant  fact  as  to  the  character 
of  either  marking  is  the  manifest  association  of 
the  two.  In  spite  of  the  great  number  of  the 
spots,  not  one  of  them  stands  isolate.  There  is 
not  a  single  instance  of  a  spot  that  is  not  con- 
nected by  a  canal  to  the  rest  of  the  dark  areas. 
This  remarkable  inability  to  stand  alone  shows 


178  MARS 

that  the  spots  and  the  canals  are  not  unrelated 
phenomena,  for  were  there  no  tie  between  them 
they  must  occasionally  exist  apart. 

Nor  is  this  all.  There  is,  apparently,  no  spot 
that  is  not  joined  to  the  rest  of  the  system,  not 
only  by  a  canal,  but  by  more  than  one;  for 
though  some  spots,  such  as  the  Fountain  of 
Youth,  have  appeared  at  first  to  be  provided 
with  but  a  single  canal  connection,  later  ob- 
servation has  revealed  concurrence  in  the  case. 
The  spots  are,  therefore,  not  only  part  and  par- 
cel of  the  canal  system,  but  terminal  phenomena 
of  the  same. 

In  the  first  place,  as  I  have  said,  there  ap- 
pears to  be  no  spot  that  has  not  two  or  more 
canals  running  to  it ;  in  the  second  place,  I  find, 
reversely,  that  apparently  no  canal  junction  is 
without  its  spot.  Such  association  is  a  most 
tell-tale  circumstance.  I  believe  the  rule  to 
have  no  exception.  The  more  prominent  junc- 
tions all  show  spots ;  and  with  regard  to  the 
less  conspicuous  ones,  it  is  to  be  remembered 
that,  as  the  canals  are  more  easy  to  make  out 
than  the  spots,  the  relative  invisibility  of  the 
latter  is  to  be  expected.  From  which  it  would 
seem  that  the  spots  are  fundamental  features  of 
the  junctions,  and  that  for  a  junction  to  be  spot- 
less is,  from  its  very  nature,  an  impossibility. 

Next  to  their  regularity  of  position  is  to  be 
remarked  their  regularity  of  form.  Their  typi- 


SPOTS  IN  THE  LIGHT  REGIONS  179 

cal  shape  seems  to  be  circular ;  for  the  better 
the  atmosphere,  the  rounder  they  look.  Under 
poor  seeing  they  show  as  irregular  patches 
smooching  the  disk,  much  as  the  canals  them- 
selves show  as  streaks ;  the  spots  differing  from 
the  canals  in  being  thicker  and  not  so  long.  As 
the  seeing  improves,  the  patches  differentiate 
themselves  into  round  dots  and  connecting  lines. 
Such  is  the  shape  of  the  spots  associated  with 
single  canals ;  th,at  is,  canals  not  double.  In  the 
case  of  the  double  canals,  the  spots  look  like 
rectangles  with  the  corners  rounded  off.  One 
of  the  most  striking  of  all  of  them  is  the  Tri- 
vium  Charontis,  which  is  nearly  square. 

Now  it  will  be  noticed  that  these  shapes  are 
as  unnatural  as  they  are  definite,  and  that  they 
all  agree  in  one  peculiarity  :  they  are  all  convex, 
not  concave,  to  the  entering  canals.  They  are 
not,  therefore,  mere  enlargements  of  the  canals, 
due  to  natural  causes ;  for,  were  the  spots  en- 
largements of  the  canals,  at  their  crossing-points 
they  should  be  more  or  less  star-shaped,  or  con- 
cave to  the  canals,  whereas  they  are  round,  or 
roundish  rectangles,  —  that  is,  convex  to  the 
same.  Such  convexity  negatives,  at  the  outset, 
their  being  purely  natural  outgrowths  of  the 
canals. 

The  majority  of  the  spots  are  from  120  to 
150  miles  in  diameter;  thus  presenting  a  cer- 
tain uniformity  in  size  as  well  as  in  shape. 


180  MAES 

There  are  also  smaller  ones,  not  more  than  75 
miles  across,  or  less. 

To  the  spot  category  belong,  apparently,  all 
the  markings  other  than  canals  to  be  seen  any- 
where on  the  continental  deserts  of  the  planet, 
from  the  great  Lake  of  the  Sun,  which  is  540 
miles  long  by  300  miles  broad,  to  the  tiny 
Fountain  of  Youth,  which  is  barely  distinguish- 
able as  a  dot.  That  all  are  fundamentally  of  a 
kind  is  hinted  at  by  their  shape  and  emphasized 
by  their  character,,  a  point  to  which  we  shall 
now  come. 

To  this  end,  we  will  start  with  an  account  of 
where  and  how  they  begin  to  show;  for,  like 
the  canals,  they  are  not  permanent  markings, 
but  temporary  phenomena.  It  is  in  the  region 
about  the  Solis  Lacus  that  they  appear  first. 
The  Solis  Lacus,  or  Lake  of  the  Sun,  is  perhaps 
the  most  striking  marking  on  Mars.  It  is  an 
oval  spot  in  lat.  28°  S.,  with  its  greater  diameter 
nearly  perpendicular  to  the  meridians,  and  en- 
circled by  an  elliptical  ring  of  reddish-ochre 
land,  which  in  turn  is  bordered  on  the  south  by 
the  blue-green  regions  of  the  south  temperate 
zone.  The  whole  configuration  is  such  as  to 
simulate  a  gigantic  eye  which  uncannily  turns 
round  upon  one  as  the  planet  slowly  revolves. 
It  is  so  conspicuous  a  feature  of  the  disk  that  it 
has  been  recognized  for  a  great  many  years. 
The  resemblance  to  an  eye  is  further  borne  out 


SPOTS  IN  THE  LIGHT  REGIONS  181 

by  a  cordon  of  canals  that  surround  it  on  the 
north.  Upon  this  cordon,  composed  of  the 
Araxes,  the  Daemon,  and  the  Agathodaemon, 
are  beaded  a  number  of  spots,  two  of  them,  the 
Phoenix  and  the  Tithonius  lakes,  being  conspic- 
uously prominent.  Closer  scrutiny  reveals  sev- 
eral more  of  the  same  sort,  only  smaller.  These 
are  all  interconnected  by  a  network  of  canals. 
Now  just  as  it  is  in  this  region  that  the  canals 
first  show,  so  likewise  is  it  here  that  the  spots 
first  make  their  appearance. 

Although  it  was  here  that  at  this  last  opposi- 
tion the  spots  were  first  seen,  it  was  not  here 
that  their  character  and  purpose  became  appar- 
ent. It  was  not  until  later  in  the  season,  when 
the  Eumenides-Orcus  began  to  give  evidence  of 
being  yet  more  peculiarly  beaded,  that  the  true 
nature  of  the  spots  suggested  itself  to  me. 

The  Eumenides-Orcus  is  a  very  long  and  im- 
portant canal,  connecting  the  Phoenix  Lake 
with  the  Trivium  Charontis.  It  is  so  long  — 
3,540  miles  from  one  end  of  it  to  the  other  — 
that,  although  it  starts  in  lat.  16°  N.  and  ends 
in  lat.  12°  S.,  it  belts  the  disk  not  many  degrees 
inclined  to  the  equator.  For  a  great  distance  it 
runs  parallel  to  the  northern  coast  of  the  Sea 
of  the  Sirens.  From  this  coast  several  canals 
strike  down  to  it ;  some  stopping  at  it,  others 
continuing  on  down  the  disk.  Especially  is  the 
western  end  of  the  sea,  called  the  Gulf  of  the 


182  MARS 

Titans,  a  point  of  departure  for  canals ;  no  less 
than  six  of  them,  and  doubtless  more,  leaving 
the  gulf  in  variously  radiating  directions.  At 
the  place  where  these  canals  severally  cross  the 
Eumenides-Orcus,  I  began  in  November  to  see 
spots.  I  also  saw  others  along  the  Pyriphlege- 
thon,  an  important  canal  leading  in  a  more 
northerly  direction  from  the  Phoenix  Lake; 
along  the  Gigas,  a  great  canal  running  from 
the  Gulf  of  the  Titans  all  the  way  to  the  Lake 
of  the  Moon ;  and  along  other  canals  in  the 
same  region.  I  then  noticed  that  the  spots  to 
the  north  of  the  Solis  Lacus  region  had  dark- 
ened, since  August,  relatively  to  the  more 
southern  ones.  In  short,  I  became  aware  both 
of  a  great  increase  in  the  number  of  spots,  and 
of  an  increase  in  tint  in  the  spots  previously 
seen. 

It  was  apparent  that  the  spots  were  part  and 
parcel  of  the  canal  system,  and  that  in  the 
matter  of  varying  visibility  they  took  after 
the  canals,  —  chronologically,  very  closely  after 
them;  for  a  comparison  of  the  two  leads  me 
to  believe  that  the  spots  make  their  appearance 
subsequent,  although  but  little  subsequent,  to 
the  canals  which  conduct  to  them. 

Furthermore,  the  spots,  like  the  canals,  grow 
in  conspicuousness  with  time.  Now,  when  we 
consider  that  nothing,  practically,  has  changed 
between  us  and  them  in  the  interval ;  that 


SPOTS  IN  THE  LIGHT  REGIONS  183 

there  has  been  no  symptom  of  cloud  or  other 
obscuration,  before  or  after,  over  the  place 
where  they  eventually  appear,  —  we  are  led  to 
the  conclusion  that,  like  the  canals,  they  grow. 

Indeed,  in  the  history  of  their  development 
the  two  features  seem  quite  similar.  Both 
grow,  and  both  follow  the  same  order  and 
method  in  their  growth.  Both  are  affected  by 
one  progressive  change  that  sweeps  over  the 
face  of  the  planet  from  the  pole  to  the  equator, 
and  then  from  the  equator  toward  the  other 
pole.  In  the  case  of  the  southern  hemisphere, 
it  is,  as  we  have  just  seen,  the  most  southern 
spots,  like  the  most  southern  canals,  that  ap- 
pear first  after  the  melting  of  the  polar  snows. 
Then  gradually  others  begin  to  show  farther 
and  farther  north.  The  quickening  of  the 
spots,  like  the  quickening  of  the  canals,  is  a 
seasonal  affair.  But  there  is  more  in  it  than 
this.  It  takes  place  in  a  manner  to  imply  that 
something  more  immediate  than  the  change  in 
the  seasons  is  concerned  in  it;  immediate  not 
in  time,  but  in  relation  to  the  result.  A  com- 
parison of  the  behavior  of  three  spots  —  the 
Phoenix  Lake,  Ceraunius,  the  spot  at  the  junc- 
tion of  the  Iris  and  the  Gigas,  and  the  Cyane 
Fons,  a  spot  where  the  Steropes,  a  newly  found 
canal,  and  the  Nilus  meet  —  will  serve  to  point 
out  what  this  something  is.  The  Phoenix  Lake 
lies  in  lat.  17°  S.,  Ceraunius  in  lat  12°  N.,  and 


184  MARS 

the  Cyane  Fons  in  lat.  28°  N.  In  August  of 
last  year,  the  first  of  these  markings  was  very 
conspicuous,  the  second  but  moderately  so, 
while  the  third  was  barely  discernible.  By 
November,  the  Phoenix  Lake  had  become  less 
salient,  Ceraunius  relatively  more  so,  and  the 
Cyane  Fons  nearly  as  evident  as  Ceraunius  had 
formerly  been.  In  the  Martian  calendar,  the 
August  observation  corresponded  to  our  20th  of 
June,  the  November  one  to  our  1st  of  August. 
All  three  spots  were  practically  within  the 
equatorial  regions.  Now,  on  the  Earth,  no  such 
marked  progression  in  seasonal  change  occurs 
within  the  tropics.  With  us,  it  is  to  all  intents 
and  purposes  equally  green  there  the  year 
through.  On  Mars  it  is  not.  Clearly,  some 
more  definite  factor  than  the  seasons  enters 
into  the  matter  upon  our  neighbor  world. 

That  this  factor  is  water  seems,  from  the  be- 
havior of  the  blue-green  areas  generally,  to  be 
pretty  certain.  But  just  as  the  so-called  seas 
are  undoubtedly  not  seas,  nor  the  canals  water- 
ways, so  the  spots  are  not  lakes.  Their  mode 
of  growth,  so  far  as  it  may  be  discerned,  con- 
firms this  conclusion.  Apparently,  it  is  not  so 
much  by  an  increase  in  size  as  by  a  deepening 
in  tint  that  they  gradually  become  recognizable. 
They  start,  it  would  seem,  as  big  as  they  are 
to  be,  but  faint  in  tone,  premonitory  shades 
of  their  future  selves.  They  then  proceed  to 


SPOTS  IN  THE  LIGHT  REGIONS  185 

substantialize  by  darkening  in  tint  throughout. 
Now,  to  deepen  thus  in  color  with  one  consent 
all  over  would  be  a  peculiar  thing  for  a  lake 
to  do.  For  had  the  lake  appreciable  depth  to 
start  with,  it  should  always  be  visible ;  and  had 
it  not,  its  bed  would  have  to  be  phenomenally 
level  to  permit  of  its  being  all  flooded  at  once. 
If,  however,  the  spots  be  not  bodies  of  water, 
but  areas  of  verdure,  their  deepening  in  tint 
throughout  is  perfectly  explicable,  since  the 
darkening  would  be  the  natural  result  of  a 
simultaneous  growth  of  vegetation.  This  in- 
ference is  further  borne  out  by  the  fact  that 
to  the  spot  class  belong  unquestionably  those 
larger  oval  markings  of  which  the  Lake  of  the 
Sun  is  the  most  conspicuous  example.  For 
both  are  associated  in  precisely  the  same  man- 
ner with  the  canal  system.  Each  spot  is  a 
centre  of  canal  connections  in  exactly  the  way 
in  which  the  Solis  Lacus  or  the  Phoenix  Lake 
itself  is.  But  the  light  coming  from  the  Solis 
Lacus  and  the  Phoenix  Lake  showed,  in  Profes- 
sor W.  H.  Pickering's  observations,  no  sign  of 
polarization  such  as  a  sheet  of  water  should 
show,  and  such  as  the  polar  sea  actually  did 
show. 

When  we  put  all  these  phenomena  together, 
—  the  presence  of  the  spots  at  the  junctions  of 
the  canals,  their  strangely  systematic  shapes, 
their  seasonal  darkening,  and,  last  but  not  least, 


186  MARS 

the  resemblance  of  the  great  continental  regions 
of  Mars  to  the  deserts  of  the  earth,  —  a  solution 
of  their  character  suggests  itself  at  once ;  to 
wit,  that  they  are  oases  in  the  midst  of  that 
desert,  and  oases  not  wholly  innocent  of  design  •, 
for,  in  number,  position,  shape,  and  behavior, 
the  oases  turn  out  as  typical  and  peculiar  a 
feature  of  Mars  as  the  canals  themselves. 

Each  phenomenon  is  highly  suggestive  con- 
sidered alone,  but  each  acquires  still  greater 
significance  from  its  association  with  the  other ; 
for  here  in  the  oases  we  have  an  end  and  object 
for  the  existence  of  canals,  and  the  most  natural 
one  in  the  world,  namely,  that  the  canals  are 
constructed  for  the  express  purpose  of  fertiliz- 
ing the  oases.  Thus  the  mysterious  rendezvous- 
ing of  the  canals  at  these  special  points  is  at 
once  explicable.  The  canals  rendezvous  so  en- 
tirely in  defiance  of  the  doctrine  of  chances 
because  they  were  constructed  to  that  end. 
They  are  not  purely  natural  developments,  but 
cases  of  assisted  nature,  just  as  they  look  to  be 
at  first  sight.  This,  at  least,  is  the  only  ex- 
planation that  fully  accounts  for  the  facts.  Of 
course  all  such  evidence  of  design  may  be 
purely  fortuitous,  with  about  as  much  proba- 
bility, as  it  has  happily  been  put,  as  that  a 
chance  collection  of  numbers  should  take  the 
form  of  the  multiplication  table. 

In   addition    to  this   general    dovetailing  of 


SPOTS  IN  THE  LIGHT  REGIONS  187 

detail  to  one  conclusion  is  to  be  noticed  the 
strangely  economic  character  of  both  the  canals 
and  the  oases  in  the  matter  of  form.  That  the 
lines  should  follow  arcs  of  great  circles,  what- 
ever their  direction,  is  as  unnatural  from  a 
natural  standpoint  as  it  would  be  natural  from 
an  artificial  one ;  for  the  arc  of  a  great  circle 
is  the  shortest  distance  from  one  point  upon 
the  surface  of  a  sphere  to  another.  It  would, 
therefore,  if  topographically  possible,  be  the 
course  to  take  to  conduct  water,  with  the  least 
expenditure  of  time  or  trouble,  from  the  one 
to  the  other. 

The  circular  shape  of  the  oases  is  as  directly 
economic  as  is  the  straightness  of  the  canals; 
for  the  circle  is  the  figure  which  incloses  the 
maximum  area  for  the  minimum  average  dis- 
tance from  its  centre  to  any  point  situated 
within  it.  In  consequence,  if  a  certain  amount 
of  country  were  to  be  irrigated,  intelligence 
would  suggest  the  circular  form  in  preference 
to  all  others,  in  order  thus  to  cover  the  greatest 
space  with  the  least  labor. 

Following  is  the  list  of  the  oases  so  far  dis- 
covered :  — 


Acherusia  Palus 
Aganippe  Fons 
Alcyonia 
Ammonium 
Aponi  Fons 


Aquae  Apollinares 
Aquae  Calidae 
Arachoti  Fons 
Arduenna 
Arethusa  Fons 


188 


MARS 


Arsia  Silva 
Arsine 
Augila 

Bandusiae  Fons 
Biblis  Fons 
Castalia  Fons 
Ceraunius 
Clepsydra  Fons 
Cyane  Fons 
Ferentinae  Lucus 
Fons  Juventae 
Gallinaria  Silva 
Hercynia  Silva 
Hibe 

Hippocrene  Fons 
Hipponitis  Palus 
Hypelaeus 
Labeatis  Lacus 
Lacus  Ismenius 
Lacus  Lunae 
Lacus  Phoenicis 
Lerne 


Lucrinus  Lacus 
Lucus  Angitiae 
Lucus  Feronia 
Lucus  Maricae 
Maeisia  Silva 
Mapharitis 
Mariotis 
Meroe 


Nitriae 
Nodus  Gordii 
Pallas  Lacus 
Propontis 
Serapium 
Sirbonis  Lacus 
Solis  Fons 
Solis  Lacus 
Tithonius  Lacus 
Trinythios 
Trivium  Charontis 
Utopia 


II.    DOUBLE    CANALS 

Even  more  markedly  unnatural  is  another 
phenomenon  of  this  most  phenomenal  system, 
of  which  almost  every  one  has  heard,  and  which 
almost  nobody  has  seen,  —  the  double  canals. 

To  see  them,  however,  all  that  is  needed  is  a 
sufficiently  steady  air,  a  sufficiently  attentive 
observer,  and  the  suitable  season  of  the  Mar- 
tian year.  When  these  conditions  are  observed, 
the  sight  may  be  seen  without  difficulty,  and  is 
every  whit  as  strange  as  Schiaparelli,  who  first 
saw  it,  has  described  it. 


DOUBLE  CANALS  189 

So  far  as  the  observer  is  concerned,  what 
occurs  is  this :  Upon  a  part  of  the  disk  where 
up  to  that  time  a  single  canal  has  been  visible, 
of  a  sudden,  some  night,  in  place  of  the  single 
canals  he  perceives  twin  canals,  —  as  like,  in- 
deed, as  twins,  if  not  more  so,  similar  both  in 
character  and  in  inclination,  running  side  by 
side  the  whole  length  of  the  original  canal, 
usually  for  upwards  of  a  thousand  miles,  of  the 
same  size  throughout,  and  absolutely  parallel  to 
each  other.  The  pair  may  best  be  likened  to 
the  twin  rails  of  a  railroad  track.  The  regu- 
larity of  the  thing  is  startling. 

In  good  air  the  phenomenon  is  quite  unmis- 
takable. The  two  lines  are  as  distinct  and  as 
distinctly  parallel  as  possible.  No  draughts- 
man could  draw  them  better.  They  are  tho- 
roughly Martian  in  their  mathematical  preci- 
sion. At  the  very  first  glance,  they  convey, 
like  all  the  other  details  of  the  canal  system, 
the  appearance  of  artificiality.  It  may  be  well 
to  state  this  here  definitely,  for  the  benefit  of 
such  as,  without  having  seen  the  canals,  in- 
dulge in  criticism  about  them.  No  one  who 
has  seen  the  canals  well  —  and  the  well  is  all- 
important  for  bringing  out  the  characteristics 
that  give  the  stamp  of  artificiality,  the  straight- 
ness  and  fineness  of  the  lines  —  would  ever 
have  any  doubt  as  to  their  seeming  artificial, 
however  he  might  choose  to  blind  himself  to 


190  MARS 

the  consequences.  An  element  akin  to  the 
comic  enters  criticism  based,  not  upon  what  the 
critics  have  seen,  but  upon  what  they  have  not. 
Books  are  reviewed  without  being  read,  to  pre- 
vent prejudice  ;  but  it  is  rash  to  carry  the  same 
admirable  broad-mindedness  into  scientific  sub- 
jects. 

In  detail  the  doubles  vary,  chiefly,  it  would 
seem,  in  the  distance  the  twin  lines  lie  apart. 
In  the  widest  I  have  seen,  the  Ganges,  six  de- 
grees separate  the  two ;  in  the  narrowest,  the 
Phison,  four  degrees  and  a  quarter,  —  not  a 
very  great  difference  between  the  extremes. 
Four  degrees  and  a  quarter  on  Mars  amount  to 
156  miles;  six  degrees,  to  220.  These,  then, 
are  the  distances  between  the  centres  of  the 
twin  canals.  Each  canal  seems  a  little  less  than 
a  degree  wide,  or  about  30  miles  in  the  nar- 
rower instances ;  in  the  broader,  a  little  more 
than  a  degree,  or  about  45  miles.  Between  the 
two  lines,  in  the  cases  where  the  gemination, 
as  it  is  called,  is  complete,  lies  reddish-ochre 
ground  similar  to  the  rest  of  the  surface  of  the 
bright  regions.  Deducting  the  two  half-widths 
of  the  bordering  canals,  we  have,  therefore,  from 
120  to  175  miles  of  clear  country  between  the 
paralleling  lines. 

This  gemination  of  a  canal  is  certainly  a  pass- 
ing strange  phenomenon.  Although,  in  steady 
air,  the  observation  is  not  a  difficult  one,  to  see 


DOUBLE  CANALS  191 

the  region  where  it  occurs  minutely  enough  for 
a  sufficient  length  of  time  to  mark  the  details 
of  the  process  is  another  matter.  I  shall  here 
give  what  I  have  been  able  to  gather  at  the 
last  opposition,  and  shall  hope  to  add  to  it  at  the 
next.  One  element  of  mystery  may  be  elimi- 
nated at  the  outset.  The  process  is  not  so  sud- 
den as  it  seems.  It  is  perceived  of  a  sudden  by 
the  observer  because  of  some  specially  favorable 
night.  But  it  has  been  for  some  time  develop- 
ing. So  much  is  apparent  from  my  observa- 
tions. Suggestions  of  duality  occurred  weeks 
before  the  thing  stood  definitely  revealed.  Fur- 
thermore, the  gemination  may  lie  concealed 
from  the  observer  some  time  after  it  is  quite 
complete,  owing  to  lack  of  favorable  atmospheric 
conditions.  For  it  takes  emphatically  steady 
air  to  see  it  unmistakably. 

The  next  point  is,  that  the  phenomenon  is 
individual  to  the  particular  canal.  Each  canal 
differs  from  its  neighbor  not  only  in  the  dis- 
tance the  lines  lie  apart,  but  in  the  time  at 
which  duplication  occurs.  The  event  seems  to 
depend  both  upon  general  seasonal  laws  govern- 
ing all  the  duplications,  and  upon  causes  intrin- 
sic to  the  canal  itself.  Within  limits,  each  canal 
doubles  at  its  own  good  time  and  after  its  own 
fashion.  For  example,  although  it  seems  to  be 
a  rule  that  north  and  south  canals  double  before 
east  and  west  ones,  nevertheless,  of  two  north 


192  MARS 

and  south  lines,  one  will  double,  the  other  will 
not,  synchronously  with  a  doubling  running  east 
and  west ;  the  same  is  true  of  those  running  at 
any  other  inclination. 

Now  this  shows  that  the  duplication  is  not  an 
optical  illusion  at  this  end  of  the  line  ;  for,  by 
any  double  refraction  here,  all  the  lines  running 
in  the  same  direction  over  the  disk  should  be 
similarly  affected,  which  they  are  not.  On 
the  contrary,  there  will  be,  say,  two  cases  of 
doubling  in  quite  different  directions  coexistent 
with  several  single  canals  that  run  the  same 
way. 

Nor  is  there  any  probability  of  its  being  a 
case  of  double  refraction  at  the  other  end  of  the 
line,  —  that  is,  in  the  atmosphere  of  Mars  ;  for 
in  that  case  it  is  hard  to  see  why  all  the  lines 
should  not  be  affected,  to  say  nothing  of  the 
fact  that,  to  render  such  double  refraction  pos- 
sible, we  must  call  upon  a  noumenon  to  help  us 
out,  as  we  know  of  no  substance  capable  of  the 
quality  upon  so  huge  a  scale.  Furthermore, 
what  is  cogent  to  the  observer,  though  of  no 
particular  weight  with  his  hearers,  the  pheno- 
menon has  no  look  of  double  refraction.  It 
looks  to  be,  what  it  undoubtedly  is,  a  double 
existence. 

Strengthening  this  conclusion  is  the  mode  of 
development  of  the  doubling.  This  appears  to 
take  place  in  two  ways,  although  it  is  possible 


DOUBLE  CANALS  193 

that  the  two  are  but  different  instances  of  one 
and  the  same  process.  Of  the  first  kind,  during 
this  last  opposition,  the  Ganges  was  an  example. 

The  Ganges  was  in  an  interesting  proto- 
plasmic condition  during  the  whole  of  last  sum- 
mer. About  to  multiply  by  fission,  it  was  not 
at  first  evident  how  this  would  take  place. 
Hints  of  gemination  were  visible  when  I  first 
looked  at  it  in  August.  It  showed  then  as  a 
very  broad  but  not  dark  swath  of  dusky  color, 
of  nearly  uniform  width  from  one  extremity  to 
the  other,  with  sides  suggestively  even  through- 
out. It  is  probable  that  they  were  then,  as 
afterward,  parallel,  and  that  the  slight  conver- 
gence apparent  at  the  bottom  was  due  simply 
to  foreshortening.  The  swath  ran  thus  north- 
northwest  all  the  way  from  the  Gulf  of  the 
Dawn  to  the  Lacus  Labeatis.  By  moments  of 
better  seeing,  its  two  sides  showed  darker  than 
its  middle ;  that  is,  it  was  already  double  in 
embryo,  with  a  dusky  middle-ground  between 
the  twin  lines. 

In  October  the  doubling  had  sensibly  pro- 
gressed. The  double  visions  were  more  fre- 
quent, and  the  ground  between  the  twin  lines 
had  grown  lighter.  By  November  the  doubling 
was  unmistakable,  and  the  mid-clarification  had 
become  nearly  complete.  It  is  to  be  remarked 
that  the  doubling  did  not  involve  the  Fons 
Juventae  and  the  canal  leading  f  it,  both  of 


194  MARS 

which  lay  well  to  the  right  of  the  Ganges.  The 
space  included  between  the  East  and  West 
Ganges  was  very  wide,  some  six  degrees.  The 
canals  themselves  were,  so  far  as  could  be  seen, 
quite  similar,  and  about  a  degree,  or  37  miles, 
wide.  Both  started  in  the  Gulf  of  the  Dawn, 
and  ran  down  to  the  lower  Lake  of  the  Moon, 
one  entering  each  side  of  the  lake  or  oasis.  Two 
thirds  of  the  way  down,  both  similarly  touched 
the  sides  of  another  oasis,  an  upper  Lacus 
Lunae  ;  the  other  I  have  called  the  Lacus  La- 
beatis.  The  length  of  each  canal  was  1200  miles. 

Except  for  fleeting  suspicions  of  gemination, 
and  for  possible  doublings  like  the  parallelism  of 
the  twTo  Hades,  the  next  canal  to  show  double 
was  the  Nectar,  which  was  so  seen  by  Mr.  Doug- 
lass on  October  4-,  and  under  still  better  seeing, 
a  few  minutes  later,  the  doubling  was  detected 
by  him  extending  straight  across  the  Solis 
Lacus.  In  the  Solis  Lacus  this  was  evidently 
a  case  of  mid-clarification.  What  occurred  in 
the  Nectar  seems  more  allied  to  the  second  class 
of  manifestations,  such  as  happened  later  with 
the  Euphrates  and  the  Phison. 

Glimpses  of  a  dual  state  in  these  canals  we 
caught  during  the  summer  and  autumn,  but  it 
was  not  till  the  November  presentation  of  the 
region  th**  "  came  out  unmistakably  twinned. 
On  the  §vjj,  that  month,  just  as  the  twilight 
was  fading  ^  tw  >•,  the  air  being  very  still  and 


PLATE  XXIII 


PRISON   AND   EUPHRATES 
(Both  double) 

NOVEMBER  18,  1894 


'£  to 


DOUBLE  CANALS  195 

the  definition  exceptional,  so  soon  as  the  sunset 
tremors  subsided,  the  Euphrates  and  its  neigh- 
bor the  Phison  I  saw  beautifully  doubled,  ex- 
actly like  two  great  railroad  tracks  with  bright 
ground  between,  each  set  extending  down  the 
disk  for  a  distance  of  1600  miles. 

After  that  evening,  whenever  the  seeing  was 
good  enough,  they  continued  to  present  the 
same  appearance.  Now,  with  them  no  process  of 
midway  clarification,  such  as  had  taken  place  in 
the  Ganges,  had  previously  made  itself  manifest. 
They  had,  indeed,  not  been  very  well  defined 
before  duplication  occurred,  but  apparently  suf- 
ficiently so  not  to  hide  such  broadening  had  it 
taken  place ;  for,  though  the  twin  canals  were 
not  as  far  apart  as  the  two  Ganges,  they  were 
quite  comparably  distant,  being,  instead  of  six, 
about  four  and  a  quarter  degrees  from  each 
other.  Evidently,  the  process  was,  hi  the  case 
of  the  Euphrates  at  least,  under  way  in  Octo- 
ber, and  even  earlier,  but  was  not  well  seen 
because  the  twin  canals  were  not  yet  dark 
enough. 

There  seem,  I  may  remark  parenthetically, 
to  be  two  other  double  canals  in  the  region  be- 
tween the  Syrtis  Major  and  the  Sabaeus  Sinus, 
one  to  the  east  of  the  Phison,  and  another 
between  the  Phison  and  the  Euphrates,  both 
debouching  at  the  same  points  as  the  Phison 
and  the  Euphrates  themselves. 


196  MARS 

On  the  19th  of  November  I  suspected  dupli- 
cation in  the  Typhon,  another  canal  in  the  same 
region.  It  looked  to  be  double,  with  dusky 
ground  between. 

On  the  21st  I  similarly  suspected  the  Jamuna 
and  the  Dardanus.  Both  looked  broad  and 
dusky,  with  very  ill-defined  condensation  at  the 
sides.  But  the  seeing  was  not  good  enough. 
On  the  22d  I  brought  my  observations  to  an 
end,  in  consequence  of  having  to  return  East. 

Exactly  what  takes  place,  therefore,  in  this 
curious  process  of  doubling,  I  cannot  pretend  to 
say.  It  has  been  suggested  that  a  progressive 
ripening  of  vegetation  from  the  centre  to  the 
edges  might  cause  a  broad  swath  of  green  to  be- 
come seemingly  two.  There  are  facts,  however, 
that  do  not  tally  with  this  view.  For  example, 
the  Ganges  was  always  broad,  but  fainter,  not 
narrower,  earlier  in  the  season.  The  Phison,  on 
the  other  hand,  went  through  no  such  process. 
Indeed,  we  are  here  very  much  in  the  dark,  cer- 
tainly very  far  off  from  what  does  take  place 
in  Martian  canal  gemination.  Perhaps  we  may 
learn  considerably  more  about  it  at  the  next 
opposition.  At  this  the  tendril  end  of  our 
knowledge  of  our  neighbor  we  cannot  expect 
hard  wood. 

From  these  observations,  and  those  of  Schia- 
parelli,  I  feel,  however,  tolerably  sure  that  the 
phenomenon  is  not  only  seasonal  but  vegetal. 


SPOTS  IN  THE  DARK  REGIONS  197 

Why  it  should  take  this  form  is  one  of  the  most 
pregnant  problems  about  the  planet.  For  it  is 
the  most  artificial-looking  phenomenon  of  an 
artificial-looking  disk. 

III.    SPOTS   IN   THE   DARK   REGIONS. 

To  return  now  from  these  outposts  of  inves- 
tigation to  our  main  subject-matter,  and  to  an- 
other phenomenon  of  more  recent  discovery 
than  the  double  canals,  and  yet  more  suggestive 
of  interpretation.  We  have  seen  what  shows  at 
one  end  of  the  canals,  their  inner  end ;  namely, 
the  oasis.  But  it  seems  that  there  is  also  some- 
thing exceptional  at  the  other.  At  the  mouth 
of  each  canal,  at  the  edge  of  the  so-called  seas, 
appears  a  curious  dark  spot,  of  the  form  of  a 
half-filled  angle ;  the  sort  of  a  mark  with  which 
one  checks  items  on  a  list.  Its  form  is  singularly 
appropriate,  according  to  mundane  ideas,  for  it 
appears  before  the  canal  itself  is  visible,  as  if  to 
mark  the  spot  where  the  canal  will  eventually 
be.  It  lies  in  the  so-called  seas,  and  looks  to  be 
of  the  same  color  as  they,  but  deeper  in  tint. 

All  the  canals  that  debouch  into  the  dark 
regions  are  provided  with  these  terminal  tri- 
angles, except  those  that  lead  out  of  long  estu- 
aries, like  the  Nilosyrtis,  the  Hiddekel,  the 
Gihon,  and  so  forth.  The  double  canals  are 
provided  with  twin  triangles.  That  the  trian- 
gular patches  are  phenomena  connected  with 


198  MARS 

the  canals  is  evident  from  the  fact  that  they 
never  appear  elsewhere.  What  exact  purpose 
they  serve  is  not  so  clear,  but  it  would  seem  to 
be  that  of  relay  stations  for  the  water  before  it 
enters  the  canals ;  what  we  see,  upon  this  sup- 
position, being,  not  the  station  or  reservoir 
itself,  but  the  specially  fertile  area  round  it. 

That,  in  addition  to  being  in  a  way  oases 
themselves,  they  serve  some  such  purpose  as  the 
above,  is  further  hinted  at  by  two  facts :  first, 
that  whereas  the  oases  develop,  apparently,  after 
the  canals  leading  to  them,  the  triangular  spots 
develop  before  the  canals  that  lead  out  of  them  ; 
second,  Mr.  Douglass  finds  that  it  is  in  them 
that  the  canals  in  the  dark  regions  terminate. 
They  are  the  end  of  the  one  system  at  the  same 
time  that  they  are  the  beginning  of  the  other. 
They  would,  therefore,  seem  to  be  way-stations 
of  some  sort  on  the  road  taken  by  the  water 
from  the  polar  cap  to  the  equator. 

Paralleling  in  appearance  the  oases  in  the 
bright  regions  are  round  spots  that  occur  at  the 
junctions  of  the  canals  in  the  dark  ones.  Speak- 
ing figuratively,  these  are  the  heads  of  the  nails 
in  the  coffin  of  the  idea  that  the  seas  are  seas ; 
since,  if  the  blue-green  color  came  from  water, 
there  could  not  be  permanent  darker  dots  upon 
it  connected  by  equally  dark  streaks.  Speaking 
unfiguratively,  this  shows  that  the  whole  system 
of  canals  and  specially  fertilized  spots  is  not 


SPOTS  IN  THE  DARK  REGIONS  199 

confined  to  the  deserts,  but  extends  in  a  modi- 
fied form  over  the  areas  of  more  or  less  vegeta- 
tion. 

There  are  thus  two  kinds  of  spots  in  the 
dark  regions :  those  on  their  borders,  and  those 
in  their  midst.  The  position  of  the  former  — 
on  the  edge  of  the  great  deserts  —  implies  a 
difference  in  kind,  further  emphasized  by  their 
shape.  Following  is  the  list  of  both  kinds  de- 
tected at  Flagstaff:  - 

SPOTS  IN  THE  DARK  REGIONS. 
Astrae  Lacus. 
Benacus  Lacus. 
Cynia  Lacus. 
Flevo  Lacus. 
Hesperidum  Lacus. 
Oxia  Palus. 
Spot  at  the  mouth  of  the  Phison. 

"  Euphrates. 

"  Daix  on  the  Mare  Icarium. 

Spot  at  the  mouth  of  the  Daix  on  the  Sabaeus  Sinus. 
Spot  on  the  Socratis  Promontorium. 
Spot  on  the  western  side  of  the  Socratis  Promontorium. 

"  Margaritifer  Sinus. 

Spot  at  the  mouth  of  the  Jamuna  on  the  Aurorae  Sinus. 

"  Ganges 

Hebe 

"  Agathodaemon        " 

"  Ambrosia  on  the  Mare  Australe. 

"  Maeander  on  the  Aonius  Sinus. 

"  Gorgon  on  the  Mare  Sirenum. 

"  Erinaeus. 

«  Titan  on  the  Sinus  Titanum. 


200  MARS 

Spot  at  the  mouth  of  the  Cophen  on  the  Mare  Cimmerium. 
"  Laestrygon  " 

«  Nereides  " 

«  Cerberus  " 

"  Chretes  " 

"  Asopus  on  the  Syrtis  Major. 

"  Arosis  « 

"  Typhon  " 

Spot  south  of  the  mouth  of  the  Typhon      " 

We  thus  perceive  that  the  blue-green  areas 
are  subjected  to  the  same  engineering  system 
as  the  bright  ones.  In  short,  no  part  of  the 
planet  is  allowed  to  escape  from  the  all-pervasive 
trigonometric  spirit.  If  this  be  Nature's  doing, 
she  certainly  here  runs  her  mathematics  into 
the  ground. 


VI 

CONCLUSION 

To  review,  now,  the  chain  of  reasoning  by 
which  we  have  been  led  to  regard  it  probable 
that  upon  the  surface  of  Mars  we  see  the  effects 
of  local  intelligence.  We  find,  in  the  first  place, 
that  the  broad  physical  conditions  of  the  planet 
are  not  antagonistic  to  some  form  of  life ;  sec- 
ondly, that  there  is  an  apparent  dearth  of  water 
upon  the  planet's  surface,  and  therefore,  if  be- 
ings of  sufficient  intelligence  inhabited  it,  they 
would  have  to  resort  to  irrigation  to  support 
life ;  thirdly,  that  there  turns  out  to  be  a  net- 
work of  markings  covering  the  disk  precisely 
counterparting  what  a  system  of  irrigation 
would  look  like ;  and,  lastly,  that  there  is  a  set 
of  spots  placed  where  we  should  expect  to  find 
the  lands  thus  artificially  fertilized,  and  behav- 
ing as  such  constructed  oases  should.  All  this, 
of  course,  may  be  a  set  of  coincidences,  signify- 
ing nothing ;  but  the  probability  points  the 
other  way.  As  to  details  of  explanation,  any 
we  may  adopt  will  undoubtedly  be  found,  on 
closer  acquaintance,  to  vary  from  the  actual 
Martian  state  of  things;  for  any  Martian  life 
must  differ  markedly  from  our  own. 


202  MARS 

The  fundamental  fact  in  the  matter  is  the 
dearth  of  water.  If  we  keep  this  in  mind,  we 
shall  see  that  many  of  the  objections  that  spon- 
taneously arise  answer  themselves.  The  sup- 
posed herculean  task  of  constructing  such  canals 
disappears  at  once ;  for,  if  the  canals  be  dug  for 
irrigation  purposes,  it  is  evident  that  what  we 
see,  and  call  by  ellipsis  the  canal,  is  not  really 
the  canal  at  all,  but  the  strip  of  fertilized  land 
bordering  it,  —  the  thread  of  water  in  the  midst 
of  it,  the  canal  itself,  being  far  too  small  to  be 
perceptible.  In  the  case  of  an  irrigation  canal 
seen  at  a  distance,  it  is  always  the  strip  of  ver- 
dure, not  the  canal,  that  is  visible,  as  we  see  in 
looking  from  afar  upon  irrigated  country  on  the 
Earth. 

We  may,  perhaps,  in  conclusion,  consider  for 
a  moment  how  different  in  its  details  existence 
on  Mars  must  be  from  existence  on  the  Earth. 
One  point  out  of  many  bearing  on  the  subject, 
the  simplest  and  most  certain  of  all,  is  the  effect 
of  mere  size  of  habitat  upon  the  size  of  the 
inhabitant ;  for  geometrical  conditions  alone  are 
most  potent  factors  in  the  problem  of  life. 
Volume  and  mass  determine  the  force  of  grav- 
ity upon  the  surface  of  a  planet,  and  this  is 
more  far-reaching  in  its  effects  than  might  at 
first  be  thought.  Gravity  on  the  surface  of 
Mars  is  only  a  little 'more  than  one  third  what 
it  is  on  the  surface  of  the  Earth.  This  would 


PLATE  XXV 


Nov.  5,  yh  23m-39m  Nov.  5,  gh-gh  i2m 

long.  114°,  lat.  —22°  long.  137°,  lat.  —22° 


an 

Nov.  6,  9h  i4m.-aim  Nov.  6,  ich  ssm-nh  aoro 

long.  142°,  lat.  —22°  long.  158°,  lat  — «a° 

DRAWINGS  OF  THE   PLANET   IN    1894 


CONCLUSION  203 

work  in  two  ways  to  very  different  conditions 
of  existence  from  those  to  which  we  are  accus- 
tomed. To  begin  with,  three  times  as  much 
work,  as  for  example,  in  digging  a  canal,  could 
be  done  by  the  same  expenditure  of  muscular 
force.  If  we  were  transported  to  Mars,  we 
should  be  pleasingly  surprised  to  find  all  our 
manual  labor  suddenly  lightened  threefold. 
But,  indirectly,  there  might  result  a  yet 
greater  gain  to  our  capabilities ;  for  if  Nature 
chose  she  could  afford  there  to  build  her  in- 
habitants on  three  times  the  scale  she  does  on 
Earth  without  their  ever  finding  it  out  except 
by  interplanetary  comparison.  Let  us  see  how. 

As  we  all  know,  a  large  man  is  more  un- 
wieldy than  a  small  one.  An  elephant  refuses 
to  hop  like  a  flea ;  not  because  he  considers  the 
act  undignified,  but  simply  because  he  cannot 
bring  it  about.  If  we  could,  we  should  all 
jump  straight  across  the  street,  instead  of  pain- 
fully paddling  through  the  mud.  Our  inability 
to  do  so  depends  upon  the  size  of  the  Earth,  not 
upon  what  it  at  first  seems  to  depend,  on  the 
size  of  the  street. 

To  see  this,  let  us  consider  the  very  simplest 
case,  that  of  standing  erect.  To  this  every-day 
feat  opposes  itself  the  weight  of  the  body 
simply,  a  thing  of  three  dimensions,  height, 
breadth,  and  thickness,  while  the  ability  to 
accomplish  it  resides  in  the  cross-section  of  the 


204  MARS 

muscles  of  the  knee,  a  thing  of  only  two  dimen- 
sions, breadth  and  thickness.  Consequently,  a 
person  half  as  large  again  as  another  has  about 
twice  the  supporting  capacity  of  that  other,  but 
about  three  times  as  much  to  support.  Standing 
therefore  tires  him  out  more  quickly.  If  his 
size  were  to  go  on  increasing,  he  would  at  last 
reach  a  stature  at  which  he  would  no  longer  be 
able  to  stand  at  all,  but  would  have  to  lie 
down.  You  shall  see  the  same  effect  in  quite 
inanimate  objects.  Take  two  cylinders  of  paraf- 
fine  wax,  one  made  into  an  ordinary  candle,  the 
other  into  a  gigantic  facsimile  of  one,  and  then 
stand  both  upon  their  bases.  To  the  small  one 
nothing  happens.  The  big  one,  however, 
begins  to  settle,  the  base  actually  made  viscous 
by  the  pressure  of  the  weight  above. 

Now  apply  this  principle  to  a  possible  inhabit- 
ant of  Mars,  and  suppose  him  to  be  constructed 
three  times  as  large  as  a  human  being  in  every 
dimension.  If  he  were  on  Earth,  he  would 
weigh  twenty-seven  times  as  much,  but  on  the 
surface  of  Mars,  since  gravity  there  is  only 
about  one  third  of  what  it  is  here,  he  would 
weigh  but  nine  times  as  much.  The  cross-sec- 
tion of  his  muscles  would  be  nine  times  as 
great.  Therefore  the  ratio  of  his  supporting 
power  to  the  weight  he  must  support  would  be 
the  same  as  ours.  Consequently,  he  would  be 
able  to  stand  with  as  little  fatigue  as  we.  Now 


CONCLUSION  205 

consider  the  work  he  might  be  able  to  do.  His 
muscles,  having  length,  breadth,  and  thickness, 
would  all  be  twenty-seven  times  as  effective  as 
ours.  He  would  prove  twenty-seven  times  as 
strong  as  we,  and  could  accomplish  twenty- 
seven  times  as  much.  But  he  would  further 
work  upon  what  required,  owing  to  decreased 
gravity,  but  one  third  the  effort  to  overcome. 
His  effective  force,  therefore,  would  be  eighty- 
one  times  as  great  as  man's,  whether  in  digging 
canals  or  in  other  bodily  occupation.  As  grav- 
ity on  the  surface  of  Mars  is  really  a  little  more 
than  one  third  that  at  the  surface  of  the  Earth, 
the  true  ratio  is  not  eighty-one,  but  about  fifty ; 
that  is,  a  Martian  would  be,  physically,  fifty- 
fold  more  efficient  than  man. 

As  the  reader  will  observe,  there  is  nothing 
problematical  about  this  deduction  whatever. 
It  expresses  an  abstract  ratio  of  physical  capa- 
bilities which  must  exist  between  the  two 
planets,  quite  irrespective  of  whether  there  be 
denizens  on  either,  or  how  other  conditions 
may  further  affect  their  forms.  As  the  reader 
must  also  note,  the  deduction  refers  to  the  pos- 
sibility, not  to  the  prpbability,  of  such  giants ; 
the  calculation  being  introduced  simply  to  show 
how  different  from  us  any  Martians  may  be,  not 
how  different  they  are. 

It  must  also  be  remembered  that  the  ques- 
tion of  their  size  has  nothing  to  do  with  the 


206  MARS 

question  of  their  existence.  The  arguments  for 
their  presence  are  quite  apart  from  any  consid- 
eration of  avoirdupois.  No  Herculean  labors 
need  to  be  accounted  for ;  and,  if  they  did,  brain 
is  far  more  potent  to  the  task  than  brawn. 

Something  more  we  may  deduce  about  the 
characteristics  of  possible  Martians,  dependent 
upon  Mars  itself,  a  result  of  the  age  of  the 
world  they  would  live  in. 

A  planet  may  in  a  very  real  sense  be  said  to 
have  life  of  its  own,  of  which  what  we  call  life 
may  or  may  not  be  a  subsequent  detail.  It  is 
born,  has  its  fiery  youth,  sobers  into  middle 
age,  and  just  before  this  happens  brings  forth, 
if  it  be  going  to  do  so  at  all,  the  creatures  on 
its  surface  which  are,  in  a  sense,  its  offspring. 
The  speed  with  which  it  runs  through  its 
gamut  of  change  prior  to  production  depends 
upon  its  size;  for  the  smaller  the  body  the 
quicker  it  cools,  and  with  it  loss  of  heat  means 
beginning  of  life  for  its  offspring.  It  cools 
quicker  because,  as  we  saw  in  a  previous  chapter, 
it  has  relatively  less  inside  for  its  outside,  and  it 
is  through  its  outside  that  its  inside  cools.  After 
it  has  thus  become  capable  of  bearing  life,  the 
Sun  quickens  that  life  and  supports  it  for  we 
know  not  how  long.  But  its  duration  is  meas- 
ured at  the  most  by  the  Sun's  life.  Now, 
inasmuch  as  time  and  space  are  not,  as  some 
philosophers  have  from  their  too  mundane  stand- 


CONCLUSION  207 

point  supposed,  forms  of  our  intellect,  but 
essential  attributes  of  the  universe,  the  time 
taken  by  any  process  affects  the  character  of 
the  process  itself,  as  does  also  the  size  of  the 
body  undergoing  it.  The  changes  brought 
about  in  a  large  planet  by  its  cooling  are  not, 
therefore,  the  same  as  those  brought  about  in  a 
small  one.  Physically,  chemically,  and,  to  our 
present  end,  organically,  the  two  results  are 
quite  diverse.  So  different,  indeed,  are  they 
that  unless  the  planet  have  at  least  a  certain 
size  it  will  never  produce  what  we  call  life, 
meaning  our  particular  chain  of  changes  or 
closely  allied  forms  of  it,  at  all.  As  we  saw  in 
the  case  of  atmosphere,  it  will  lack  even  the 
premise  to  such  conclusion. 

Whatever  the  particular  planet's  line  of  devel- 
opment, however,  in  its  own  line,  it  proceeds  to 
greater  and  greater  degrees  of  evolution,  till 
the  process  stops,  dependent,  probably,  upon  the 
Sun.  The  point  of  development  attained  is,  as 
regards  its  capabilities,  measured  by  the  planet's 
own  age,  since  the  one  follows  upon  the  other. 

Now,  in  the  special  case  of  Mars,  we  have  be- 
fore us  the  spectacle  of  a  world  relatively  well 
on  in  years,  a  world  much  older  than  the  Earth. 
To  so  much  about  his  age  Mars  bears  evidence 
on  his  face.  He  shows  unmistakable  signs  of 
being  old.  Advancing  planetary  years  have  left 
their  mark  legible  there.  His  continents  are  all 


208  MARS 

smoothed  down ;  his  oceans  have  all  dried  up. 
Teres  atque  rotundus,  he  is  a  steady-going  body 
now.  If  once  he  had  a  chaotic  youth,  it  has 
long  since  passed  away.  Although  called  after 
the  most  turbulent  of  the  gods,  he  is  at  the 
present  time,  whatever  he  may  have  been  once, 
one  of  the  most  peaceable  of  the  heavenly  host. 
His  name  is  a  sad  misnomer;  indeed,  the  an- 
cients seem  to  have  been  singularly  unfortunate 
in  their  choice  of  planetary  cognomens.  With 
Mars  so  peaceful,  Jupiter  so  young,  and  Venus 
bashfully  draped  in  cloud,  the  planet's  names 
accord  but  ill  with  their  temperaments. 

Mars  being  thus  old  himself,  we  know  that 
evolution  on  his  surface  must  be  similarly  ad- 
vanced. This  only  informs  us  of  its  condition 
relative  to  the  planet's  capabilities.  Of  its 
actual  state  our  data  are  not  definite  enough  to 
furnish  much  deduction.  But  from  the  fact  that 
our  own  development  has  been  comparatively 
a  recent  thing,  and  that  a  long  time  would  be 
needed  to  bring  even  Mars  to  his  present  geolo- 
gical condition,  we  may  judge  any  life  he  may 
support  to  be  not  only  relatively,  but  really 
older  than  our  own. 

From  the  little  we  can  see,  such  appears  to 
be  the  case.  The  evidence  of  handicraft,  if  such 
it  be,  points  to  a  highly  intelligent  mind  behind 
it.  Irrigation,  unscientifically  conducted,  would 
not  give  us  such  truly  wonderful  mathematical 


PLATE  XXVI 


Nov.  to,  gh  57m-ioh  i8m 
long.  112°,  lat.  — 22° 


Nov.  10,  ich  32111-37111 
long.  117°,  lat.  —22° 


Nov.  10,  ich  SOHI-I  ih 
long.  122°,  lat.  —22° 


DRAWINGS   OF  THE  PLANET   IN   1894 


CONCLUSION  209 

fitness  in  the  several  parts  to  the  whole  as  we 
there  behold.  A  mind  of  no  mean  order  would 
seem  to  have  presided  over  the  system  we  see, 
—  a  mind  certainly  of  considerably  more  com- 
prehensiveness than  that  which  presides  over 
the  various  departments  of  our  own  public 
works.  Party  politics,  at  all  events,  have  had 
no  part  in  them  ;  for  the  system  is  planet  wide. 
Quite  possibly,  such  Martian  folk  are  possessed 
of  inventions  of  which  we  have  not  dreamed, 
and  with  them  electrophones  and  kinetoscopes 
are  things  of  a  bygone  past,  preserved  with 
veneration  in  museums  as  relics  of  the  clumsy 
contrivances  of  the  simple  childhood  of  the  race. 
Certainly  what  we  see  hints  at  the  existence  of 
beings  who  are  in  advance  of,  not  behind  us,  in 
the  journey  of  life. 

Startling  as  the  outcome  of  these  observations 
may  appear  at  first,  in  truth  there  is  nothing 
startling  about  it  whatever.  Such  possibility 
has  been  quite  on  the  cards  ever  since  the  ex- 
istence of  Mars  itself  was  recognized  by  the 
Chaldean  shepherds,  or  whoever  the  still  more 
primeval  astronomers  may  have  been.  Its 
strangeness  is  a  purely  subjective  phenomenon, 
arising  from  the  instinctive  reluctance  of  man 
to  admit  the  possibility  of  peers.  Such  would 
be  comic  were  it  not  the  inevitable  consequence 
of  the  constitution  of  the  universe.  To  be  shy 
of  anything  resembling  himself  is  part  and  par- 


210  MARS 

eel  of  man's  own  individuality.  Like  the  savage 
who  fears  nothing  so  much  as  a  strange  man, 
like  Crusoe  who  grows  pale  at  the  sight  of  foot- 
prints not  his  own,  the  civilized  thinker  instinc- 
tively turns  from  the  thought  of  mind  other 
than  the  one  he  himself  knows.  To  admit  into 
his  conception  of  the  cosmos  other  finite  minds 
as  factors  has  in  it  something  of  the  weird. 
Any  hypothesis  to  explain  the  facts,  no  matter 
how  improbable  or  even  palpably  absurd  it  be, 
is  better  than  this.  Snow-caps  of  solid  carbonic 
acid  gas,  a  planet  cracked  in  a  positively  mono- 
maniacal  manner,  meteors  ploughing  tracks 
across  its  surface  with  such  mathematical  pre- 
cision that  they  must  have  been  educated  to 
the  performance,  and  so  forth  and  so  on,  in 
hypotheses  each  more  astounding  than  its  pre- 
decessor, commend  themselves  to  man,  if  only 
by  such  means  he  may  escape  the  admission  of 
anything  approaching  his  kind.  Surely  all  this 
is  puerile,  and  should  as  speedily  as  possible  be 
outgrown.  It  is  simply  an  instinct  like  any 
other,  the  projection  of  the  instinct  of  self-pre- 
servation. We  ought,  therefore,  to  rise  above 
it,  and,  where  probability  points  to  other  things, 
boldly  accept  the  fact  provisionally,  as  we  should 
the  presence  of  oxygen,  or  iron,  or  anything 
else.  Let  us  not  cheat  ourselves  with  words. 
Conservatism  sounds  finely,  and  covers  any 
amount  of  ignorance  and  fear. 


CONCLUSION  211 

We  must  be  just  as  careful  not  to  run  to  the 
other  extreme,  and  draw  deductions  of  purely 
local  outgrowth.  To  talk  of  Martian  beings  is 
not  to  mean  Martian  men.  Just  as  the  proba- 
bilities point  to  the  one,  so  do  they  point  away 
from  the  other.  Even  on  this  Earth  man  is  of 
the  nature  of  an  accident.  He  is  the  survival 
of  by  no  means  the  highest  physical  organism. 
He  is  not  even  a  high  form  of  mammal.  Mind 
has  been  his  making.  For  aught  we  can  see, 
some  lizard  or  batrachian  might  just  as  well 
have  popped  into  his  place  early  in  the  race, 
and  been  now  the  dominant  creature  of  this 
Earth.  Under  different  physical  conditions,  he 
would  have  been  certain  to  do  so.  Amid  the 
surroundings  that  exist  on  Mars,  surroundings 
so  different  from  our  own,  we  may  be  practi- 
cally sure  other  organisms  have  been  evolved 
of  which  we  have  no  cognizance.  What  man- 
ner of  beings  they  may  be  we  lack  the  data 
even  to  conceive. 

For  answers  to  such  problems  we  must  look 
to  the  future.  ^That  Mars  seems  to  be  inhabited 
is  not  the  last,  but  the  first  word  on  the  sub- 
ject. More  important  than  the  mere  fact  of 
the  existence  of  living  beings  there,  is  the 
question  of  what  they  may  be  like.  Whether 
we  ourselves  shall  live  to  learn  this  cannot,  of 
course,  be  foretold.^  One  thing,  however,  we 
can  do,  and  that  speedily  :  look  at  things  from  a 
standpoint  raised  above  our  local  point  of  view  ; 


212  MAKS 


free  our  minds  at  least  from  the  shackles  that 
of  necessity  tether  our  bodies;  recognize  the 
possibility  of  others  in  the  same  light  that 
we  do  the  certainty  of  ourselves.  That  we  are 
the  sum  and  substance  of  the  capabilities  of  the 
cosmos  is  something  so  preposterous  as  to  be- 
exquisitely  comic.  We  pride  ourselves  upon 
being  men  of  the  world,  forgetting  that  this  is 
but  objectionable  singularity,  unless  we  are,  in 
some  wise,  men  of  more  worlds  than  one.  For, 
after  all,  we  are  but  a  link  in  a  chain.  Man  is 
merely  this  earth's  highest  production  up  to 
date.  That  he  in  any  sense  gauges  the  possi- 
bilities of  the  universe  is  humorous.  He  does 
not,  as  we  can  easily  foresee,  even  gauge  those 
of  this  planet.  He  has  been  steadily  bettering 
from  an  immemorial  past,  and  will  apparently 
continue  to  improve  through  an  incalculable 
future.  Still  less  does  he  gauge  the  universe 
about  him.  He  merely  typifies  in  an  imperfect 
way  what  is  going  on  elsewhere,  and  what,  to  a 
mathematical  certainty,  is  in  some  corners  of 
the  cosmos  indefinitely  excelled. 

If  astronomy  teaches  anything,  it  teaches 
that  man  is  but  a  detail  in  the  evolution  of  the 
universe,  and  that  resemblant  though  diverse 
details  are  inevitably  to  be  expected  in  the  host 
of  orbs  around  him.  He  learns  that,  though  he 
will  probably  never  find  his  double  anywhere, 
he  is  destined  to  discover  any  number  of  cousins 
scattered  through  space. 


APPENDIX 

NOTE  I 

The  critical  velocity  at  the  surfaces  of  the  planets  is  found 
as  follows  :  — 

Using  the  usual  symbols  we  have  : 
fdt  =  dv 
.•.  fds  =  vdv. 

And  as  /  =  ^?,  since  the  force  tends  to  decrease  the  cobrdi- 
s 

mds         , 
nates,  this  becomes  --  j-  =  vdv. 

Integrating  : 

—  =  £  r3  -f-  c,  of  which  the  definite  integral  from  sl  to  sa  is 


Hence,  since  at  infinity  the  velocity  is  0,  the  equation  for  a 
fall  to  a  planet's  surface  from  infinity  is 


r  being  the  radius  of  the  planet  and  v  the  velocity  acquired  at 
its  surface  from  a  fall  from  infinity,  which  is  the  same  as  the 
velocity  needed  for  projection  from  its  surface  to  infinity. 

To  find  m  we  have  in  the  case  of  the  Earth  </=  32  ft.  a  second 
at  its  surface  ;  this  gives  us  m  in  terms  of  g,  that  is,  /.  For  the 
other  planets  we  need  only  to  introduce  their  masses  and  radii  in 
terms  of  those  of  the  Earth  and  then  multiply  the  value  for  the 
Earth  by  the  square  root  of  the  ratio. 

The  result  is  that  we  find  the  critical  velocity  for  the  several 
planets  and  for  the  Sun  to  be  as  follows  :  — 

Mercury  2.2  miles  a  second  (probable  value). 

Venus  6.6      "     "       " 

Earth  6.9      "      "       " 

Moon  1.5      "     "      " 


214  APPENDIX 

Mars  8.1  miles  a  second. 

Jupiter  37.        "     "      "        (mean  value). 

Saturn  22.        "      "       "              "        " 

Uranus  13.        "     "       "              "         " 

Neptune  14.        "     "      «             "        " 

Sun  382.        «      "       « 

While  the  probable  maximum  speed  of  the  molecules  of  some 
of  the  commoner  gases  at  0°  Cent,  are  as  follows  :  — 

Hydrogen  7.4  miles  a  second. 

Water  vapor  2.5      "     "      " 

Nitrogen  2.0      "     "       " 

Oxygen  1.8      "     "       " 
Carbonic  dioxide      1.6      "     "      " 


NOTE  II 

The  change  in  the  apparent  size  of  the  equatorial  diam- 
eter as  compared  with  the  polar  one  as  the  phase  increased, 
suggesting  the  unconscious  measurement  of  a  twilight  upon 
the  planet,  becomes  still  more  striking  when,  in  addition  to 
the  October-November  measures  mentioned  in  the  text,  the 
measures  from  July  to  October  are  considered  in  connection 
with  them.  Tabulated  chronologically,  the  whole  are  as  fol- 
lows :  — 

MEANS 

POLAR  DIAMETERS 

Cor.  for  Cor.  for 

ref.  irr.  Pw>v>  Angle        ref.  irr. 

tilt  and  f™b;  ofg          tilt  and 

phase  phase         phase 

Irr.  0".10  Irr.  0".15 

July  (6  to  22  inc.)  9.976  0".13  0°  9.933 

Aug.  (11  to  21  inc.)  9.362  0".04  0°  9.325 

Sept.  (20  to  Oct.  5  inc.)  9.401  0".012  0°  9.355 

Oct.  (12  &  24  to  30  inc.)  9.375  0".028  1°  9.336 

Oct.  (15  to  23  inc.)  9.379  0".011  2°.5  9.339 

Oct.  (12  &  24  to  30  inc.)  9.375  0".028  1°  9.336 

Nov.  (2  to  21  inc.)  9.390  0".012  4°  9.350 


APPENDIX  215 

EQUATORIAL  DIAMETERS 

July  (6  to  22  inc.)  9.691)  0".ll  )  46°.5  9.672 

Aug.  (11  to  21  inc.)  9.666  >  9'680  0".15  J  °"<08  41°  9.645 

Sept.(20  to  Oct.  5)  9.523  0".010  20°.5  9.490 

Oct.  (12  &  24  to  30  inc.)  9.457  0".016  7°  9.417 

Oct.  (15  to  23  inc.)  9.429  0".010  1°  9.385 

Oct.  (12  &  24  to  30  inc.)  9.457  0".016  7°  9.417 

Nov.  (2  to  21  inc.)  9.545  0".015  19°  9.514 

It  will  be  seen  that,  except  for  the  July  value,  the  size  of 
the  polar  diameter  comes  out  essentially  the  same  through- 
out. Now,  during  July  the  polar  cap  was  very  large,  and 
covered  the  southern  part  of  the  disk  at  the  point  where  the 
polar  diameter  was  measured.  As  it  was  much  brighter 
than  the  rest  of  the  disk,  its  irradiation  must  have  been  cor- 
respondingly great,  and  this  would  have  had  the  effect  of 
increasing  the  apparent  length  of  the  polar  diameter  beyond 
its  true  value. 

The  equatorial  measures,  on  the  other  hand,  show  a  sys- 
tematic increase  as  the  phase  increased;  and  they  do  this 
on  both  sides  of  opposition.  The  increase,  it  will  be  noticed, 
is  much  greater  than  the  probable  errors  of  observation. 


NOTE  III 

As  the  statement  has  been  widely  circulated  that  recent 
spectroscopic  observations  negative  an  atmosphere  on  Mars, 
it  may  be  well  to  mention  in  a  note  that  the  observations  in 
question  neither  affirm  nor  deny  its  presence,  as  their  self- 
disclosed  measure  of  precision,  J  of  an  atmosphere,  proves 
them  incapable  of  it.  They  simply  concur  in  showing  that 
atmosphere  to  be  thin.  As  a  matter  of  fact,  if  spectroscopic 
observations  did  deny  the  existence  of  an  atmosphere  on 
Mars,  such  assertion  would  be  fatal,  not  to  the  atmosphere, 
but  to  the  observer  or  his  instrument,  as  the  existence  of  an 
atmosphere  is  demonstrated  by  the  fundamental  laws  of 


216  APPENDIX 

physics,  inasmuch  as  no  change  could  take  place  on  the  plan- 
et's sui'face  without  it,  and  that  changes  do  take  place  is 
undeniable.  (See  page  31  et  seq.) 


NOTE  IV 

Mars  has  two  satellites,  discovered  by  Hall  in  1877,  and 
known  as  Deimos  (Dread)  and  Phobos  (Fear),  named  in 
keeping  with  the  God  of  "War. 

Deimos,  at  a  distance  of  14,600  miles  from  the  planet's 
centre,  makes  his  circuit  in  30  hours  and  18  minutes  ;  Phobos, 
at  a  distance  of  5,800,  in  7  hours  and  39  minutes.  As  Mars 
himself  rotates  in  24  hours  and  39  minutes,  Phobos  goes 
round  the  planet  faster  than  the  planet  turns  upon  itself, 
and,  in  consequence,  would  appear  to  any  observers  on  the 
planet's  surface  to  break  the  otherwise  universal  conformity 
of  stellar  motions  by  rising  in  the  west  and  setting  in  the 
east.  Deimos,  too,  is  just  as  unconventional  in  its  way, 
for  it  remains  for  two  days  at  a  time  about  the  horizon. 
Furthermore,  with  each,  owing  to  its  nearness  to  the  planet, 
its  distance  from  any  place  on  the  surface  varies  at  different 
times,  and  with  its  distance  varies  its  apparent  size  in  a  some- 
what startling  manner. 

As  for  themselves,  they  are  very  minute  bodies,  though 
not  so  difficult  to  see  as  is  commonly  stated.  In  the  clear 
air  of  Arizona,  both  were  conspicuous  objects.  They  appear 
as  stars  of  about  the  12th  and  10th  magnitudes  respectively ; 
Phobos  being  much  larger,  relatively  to  Deimos,  than  its 
hitherto  accepted  value  would  indicate.  Observations  at 
Flagstaff  by  both  Mr.  Douglass  and  by  me  agree  in  making 
its  relative  brilliancy  such  as  to  give  it  a  diameter  about  3.6 
times  that  of  Deimos.  It  is  not  usually  so  conspicuous  as 
Deimos,  in  spite  of  its  size,  because  of  its  proximity  to  the 
planet,  and  the  consequent  much  greater  illumination  of 
the  field  upon  which  it  is  seen.  Considering  their  most 
probable  albedoes  as  somewhat  less  than  that 'of  our  moon, 


APPENDIX  217 

•>ve  find  from  their  stellar  magnitudes,  taking  the  stellar 
magnitude  found  for  Deimos  by  Pickering  in  1877  as  basis, 
their  diameters  to  be,  — 

Deimos,  about  10  miles  ; 

Phobos,  about  36  miles. 

Phobos  would  thus,  at  its  closest  approach  to  the  surface  of 
the  planet,  that  is,  when  it  was  in  the  zenith,  just  show  a 
disk  like  the  Moon.  Otherwise  both  satellites  would  appear 
as  stars. 

Neither  satellite  shares  the  red  tint  of  the  planet. 


NOTE  V. 

As  the  means  employed  in  any  astronomical  observation 
are  of  interest,  I  may  add  that  the  telescope  used  in  these 
researches  was  an  18-inch  refractor,  made  by  Brashear,  of 
Alleghany,  Pa.,  the  largest  he  has  yet  made.  The  powers 
used  varied  from  320  to  1305  diameters,  the  usual  ones  be- 
ing, for  visual  purposes,  440  and  617,  and,  for  micrometric 
measurements,  862.  There  is,  not  unnatui'ally,  much  mis- 
conception prevalent  as  to  the  magnification  possible  in  a 
telescope.  The  highest  powers  of  a  glass  can  never  be  used 
on  planetary  detail,  as  the  tremors  of  the  air  blur  the  image. 
Thus  we  come  back  again  to  the  question  of  atmosphere, 
which  is  indeed  the  crux  observationis.  With  regard  to 
work  on  the  planets,  the  important  point  about  an  observa- 
tory is  not  so  much  what  is  its  lens  as  what  is  its  location. 


0°         10°         20°        30°        40°         50°         60°         70°        80°         90°        100°      110"       1JU° 


PLAI 


15U         160         170         180         19 


MAP 
on  Merca 


XXIV 


200°  210°   220°   230°   240°   250°   260°   270    280   290°   300   310    320    330    340    350   360 

-1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 T— 


P.L. 


'  MARS 
s  Projection 


LOWKI.L  OBSERVATORY 
Flagstaff,  A.  T.  1895 


INDEX  OF  NAMES  ON  THE  MAP  OF  MARS 

ARRANGED  ALPHABETICALLY 

REGIONS 


No.       NAME 

No.        NAME 

No.       NAME 

100  Aonius  Sinus 

236  Japygia 

286  Ophir 

7  Argyre 
168  Atlantis 
15  Aurorae  Sinus 

225  Lemuria 
207  Libya 
176  Mare  Chronium 

9  Protei  Regio 
6  Pyrrhae  Kegio 
3  Sabaeus  Sinus 

287  Ausonia 

165  Mare  Cimmerium 

2  Socratis    Promonto- 

4 Deucalionis  Regio 
263  Edom  Promontorium 

285  Mare  Erythraeum 
2S3  Mare  Icarium 

rium 
233  Syrtis  Major 

194  Elysium 

173  Mare  Sirenum 

237  Solis  Promontorium 

1  Fastigium  Arm 
229  Hadriaticum  Mare 
240  Hammonis  Cornu 

210  Mare  Tyrrhenum 
20  Margaritifer  Sinus 
103  Memnonia 

209  Syrtis  Parva 
27  Tempe 
92  Thyle  I. 

275  Hellas 

6  Noachis 

177  Thyle  II. 

211  Hesperia 

277  Oenotria 

267  Xisuthri 

205  Isidis  Kegio 

88  Ogygis  Regio 

CANALS 

No.       NAME 

No.       NAME 

No.       NAME 

271  Acalandrus 

37  Baetis 

264  Denteronilus 

84  Acampsis 
10  Acesines 

86  Bathys 
159  Bautis 

172  Digentia 
235  Dosaron 

119  Achana 

143  Belus 

93  Drahonus 

222  Achates 

193  Boreas 

107  Elison 

199  Achelous 

201  Boreosyrtis 

74  Eosphorns 

284  Acheron 

129  Brontes 

18  Erannoboas 

90  Acis 

16  Caicus 

160  Erebus 

238  Aeolus 
76  Aesis 

189  Cambyses 
22  Cantabras 

141  Erinaeus 
226  Erymanthus 

192  Aethiops 
43  Agathodaemon 

232  Carpis 
239  Casuentus 

104  Erynnis 
256  Eulaeua 

273  Alpheus 

55  Catarrhactes 

114  Eumenides 

87  Ambrosia 

94  Cayster 

193  Eunostos 

203  Amentb.es 

221  Centrites 

253  Euphrates 

12  Amphrysus 

218  Cephissus 

140  Eurvmedon 

64  Amystis 

186  Cerberus 

213  Eurypus 

61  Anapus 

14  Cestrus 

142  E  venue 

161  Antaeus 

182  Chaboras 

67  Fortunae 

242  Anubis 

184  Chretes 

179  Gaesus 

79  Araxes 

42  Chrysas 

215  (Jalaesus 

144  Arges 

49  Chrjsorrhoas 

197  Galaxias 

244  Arosis 
250  Arsanias 

212  Cinyphus 
47  Clitunmus 

36  Ganges 
48  Ganymede 

62  Artanes 

64  Clodianus 

13  Garrhuenus 

243  Asopus 

160  Cophen 

122Gigas 

245  Astaboras 

44  Coprates 

266  Gihon 

204  Astapus 

40Corax 

63  Glaucus 

166  Atax 

164  Cyanetw 

105  Gorgon 

224  Athesis 
163  Avernus 

91  Cyrus 
77  Daemon 

146  Gyes 
163  Hades 

73  ATUS 

260  Daix 

70  Halys 

162  Axius 

268  Daradaz 

170  Harpasus 

148  Axon 

26  Dardanus 

88  Hebe 

67  Bactrus 

19  Dargamanes 

181  HeUMon 

220     INDEX  OF  NAMES  ON  THE  MAP  OF  MARS 


No.       NAME 

No.        NAMB 

No.       NAMB 

171  Heratemis 

263  Margus 

82  Phasis 

101  Herculis  Columnae 

127  Medus 

247  Phison 

261  Hiddekel 

106  Medusa 

251  Protonilus 

17  Hipparis 
231  Hippus 
234  Hyctanis 

99  Mogrus 
39  Nectar 
135  Neda 

175  Psychrus 
121  Pyriphlegethon 
220  Rha 

32  Hydaspes 
34  Hydraotes 

206  Nepenthes 
183  Nereides 

178  Scamander 
223  Sesamus 

11  Hydriacus 

167  Nestus 

174  Simois 

227  Hylias 

269  Neudrus 

111  Sirenius 

272  Hyllus 

29  Nilokeras 

254  Sitacus 

31  Hyphasis 

246  Nilosyrtis 

130  Steropes 

35  Hypsas 
102  Hyscus 

61  Nilus 
188  Nymphaeus 

196  Styx 
89  Surius 

30  Indus 

8  Oceanus 

157  Tartarus 

68  Iris 

21  Ochus 

228  Tedanius 

95  Isis 

180  Opharus 

112  Thennodon 

28  Jamuna 

149  Orcus 

133  Thyanis 

80  Jaxartes 

255  Orontes 

125  Titan 

257  Labotas 

230  Orosines 

72  Tithonius 

155  Laestrygon 

24  Oxus 

208  Triton 

166  Leontes 

191  Pactolus 

276  Tyndis 

202  Lethes 

169  Padargus 

241  Typhon 

139  Liris 

66  Palamnus 

110  Ulysses 

81  Maeander 

108  Parcae 

66  Uranius 

270  Magon 
97  Malva 

274  Peneus 

219  Xanthus 

OASES 

No.       NAMB 

No.       NAMB 

No.       NAMB 

69  Acherusia  Palus 

288  Daphne 

41  Maeisia  Silva 

109  Aganippe  Fons 

124  Ferentinae  Lucus 

69  Mapharitis 

128  Alcyonia 

214  Flevo  Lacus 

118  Mareotis 

136  Ammonium 

46  Fons  Juventae 

63  Meroe 

195  Aponi  Fons 

83  Gallinaria  Silva 

45  Messeis  Fons 

158  Aquae  Apollinares 
200  Aquae  Calidae 

116  Hercynia  Silva 
216  Hesperidum  Lacus 

132  Nitriae 
113  Nodus  Gordil 

131  Arachoti  Fons 

147  Hibe 

280  Nessonis  Lacus 

116  Arduenna 

68  Hippocrene  Fons 

282  Nuba  Lacus 

262  Arethusa  Fons 

249  Hipponitis  Palus 

23  Oxia  Palus 

278  Arsia  Silva 

151  Hypelaeus 

279  Palicorum  Lacus 

117  Arsine 

52  Labeatis  Lacus 

25  Pallas  Lacus 

96  Astrae  Lacus 

252  Lacus  Ismenius 

162  Propontis 

134  Augila 

50  Lacus  Lunae 

265  Serapium 

123  Bandusiae  Fons 

78  Lacus  Phoenicis 

248  Sirbonis  Lacus 

98  Benacus  Lacus 

281  Lausonius  Lacus 

269  Solis  Fons 

120  Biblis  Fons 

75  Lerne 

85  Solis  Lacus 

146  Castalia  Fons 

190  Lucrinus  Lacus 

71  Tithonius  Lacus 

65  Ceraunius 

185  Lucus  Angitiae 

126  Trinythios 

187  Clepsydra  Fons 
60  Cyane  Fons 

33  Lucus  Feronia 
138  Lucus  Maricae 

154  Trivium  Charontis 
137  Utopia 

217  Cynia  Lacus 

INDEX  OF  NAMES  ON  THE  MAP  OF  MAES 

ARRANGED  NUMERICALLY 


1  Fastigium  Aryn 

66  Uranius 

112  Thermodon 

2  Socratis    Proinonto- 

67  Bactrus 

113  Nodus  Gordii 

rium 

68  Hippocrene  Fons 

114  Eumenides 

3  Sabaeus  Sinus 

59  Acherusia  Palus 

115  Arduenna 

4  Deucalionis  Regio 
6  Pyrrhae  Regio 

60  Cyane  Fons 
61  Anapus 

116  Hercynia  Silra 
117  Areine 

6  Noachis 

62  Artanes 

118  Mareotis 

7  Argyre 

63  Glaucus 

119  Achana 

8  Oceanus 

64  Clodianus 

120  Bib)  is  Fons 

9  Protei  Regio 
10  Acesines 

66  Ceraunius 
66  Palamnus 

121  Pyriphlegethon 
122  Gigas 

11  Hydriacus 

67  Fortunae 

123  Bandusiae  Fons 

12  Amphrysus 

68  Iris 

124  Ferentiiiae  Lucus 

13  Garrhuenus 
14  Oestrus 

69  Mapharitis 
70  Halys 

125  Titan 
126  Trinythios 

15  Aurorae  Sinus 

71  Tithonius  Lacus 

127  Medus 

16  Caicus 

72  Tithonius 

128  Alcyonia 

17  Hipparis 

73  Avus 

129  Brontes 

18  Erannoboas 

74  Eosphorus 

130  Steropes 

19  Dargainanes 

75  Lerne 

131  Arachoti  Fons 

20  Margaritifer  Sinus 
21  Ochus 

76  Aesis 
77  Daemon 

132  Nitriae 
133  Thyanis 

22  Cantabras 

78  Lacus  Phoenicia 

134  Augila 

23  Oxia  Palus 

79  Araxes 

135  Neda 

24  Oxus 

80  Jaxartes 

136  Ammonium 

25  Pallas  Lacus 

81  Maeander 

137  Utopia 

26  Dardanus 

82  Phasis 

138  Lucus  Maricae 

27  Tempe 

83  Gallinaria  Silra 

139  Liris 

28  Jamuna 

84  Acampsis 

140  Eurymedon 

29  Nilokeras 

86  Solis  Lacus 

141  Erinaeus 

30  Indus 

86  Bathys 

142  Evenus 

31  Hyphasis 

87  Ambrosia 

143  Belus 

32  Hvdaspes 
33  Lucus  Feronia 

88  Ogygis  Regio 
89  Surius 

144  Arges 
145  Gyes 

34  Hydraotes 

90  Acis 

146  Castalia  Fons 

35  Hypsas 

91  Cyrus 

147  Hibe 

36  Ganges 
37  Baetis 

92  Thyle  I. 
93  Drahonus 

148  Axon 
149  Orcus 

38  Hebe 

94  Cayster 

160  Erebus 

39  Nectar 

95  Isis 

151  Hypelaeus 

40  Corax 

96  Astrae  Lacus 

162  Propontis 

41  Maeisia  Silva 

97  Malra 

163  Hades 

42  Chrysas 

98  Benacus  Lacus 

164  Trivium  Charontis 

43-  Agatbodaemon 

99  Mogrus 

44  Coprates 

100  Aonius  Sinus 

166  Atal  ryg°I 

46  Meggels  Fons 

101  Ilerculis  Columnae 

157  Tartarus 

46  Fons  Jurentae 
47  Clitumnus 

102  Hyscus 
103  .Momnonia 

168  Aquae  Apollinares 
169  Bautis 

48  Ganymede 
49  Chrysorrhoas 

104  Erynnis 
106  Gorgon 

160  Cophen 
161  Antaeus 

60  Lacus  Lunae 

106  Medusa 

162  Axius 

61  Nilus 

107  Elison 

163  Arernns 

52  Labeatis  Lacus 

108  Parcae 

164  Cyaneus 

63  Meroe 
64  Amvstis 

109  Aganippe  Fons 
110  Ulysses^ 

166  Hare  Cimmerium 
Ufl  [MM!* 

65  Catarrhactes 

111  Sirenius 

167  Nestui 

222    INDEX  OF  NAMES  ON  THE  MAP  OF  MARS 


168  Atlantis 
169  Padargus 
170  Harpasus 

209  Syrtis  Parva 
210  Mare  Tyrrhenum 
211  Hesperia 

249  Hipponitis  Palus 
250  Arsauias 
251  Protonilus 

171  Heratemis 

212  Cinyphus 

252  Lacus  Ismenius 

172  Digentia 

213  Eurypus 

263  Euphrates 

173  Mare  Sirennm 

214  Fleyo  Lacus 

254  Sitacus 

174  Simois 

215  Galaesus 

255  Orontes 

175  Psychrus 

216  Hesperidum  Lacus 

256  Eulaeus 

176  Mare  Chronium 

217  Cynia  Lacus 

257  Labotas 

177  Thyle  II. 

218  Cephissus 

258  Daradax 

178  Scamander 

219  Xanthus 

259  Solis  Fons 

179  Gaesus 

220  Kha 

260  Diiix 

180  Opharus 

221  Centrites 

261  Hiddekel 

181  Helisson 

222  Achates 

262  Arethusa  Fons 

182  Chaboras 

223  Sesamus 

263  Margus 

183  Nereides 

224  Athesis 

264  Deuteronilus 

184  Chretes 

225  Lemuria 

265  Serapium 

185  Lucus  Angitiae 
186  Cerberus 

226  Erymanthus 
227  Hylias 

266  Gihon 
267  Xisuthri 

187  Clepsydra  Fons 

228  Tedanius 

268  Edom  Promontoriu: 

188  Nymphaeus 

229  Hadriaticum  Mare 

269  Neudrus 

189  Cambyses 

230  Orosines 

270  Magon 

190  Lucrinus  Lacus 

231  Hippus 

271  Acalandrus 

191  Pactolus 

232  Carpis 

272  Hyllus 

192  Aethiops 

233  Syrtis  Major 

273  Alpheus 

193  Eunostos 

234  Hyctanis 

274  Peneus 

194  Elysium 

235  Dosaron 

275  Hellas 

195  Aponi  Fons 

196  Styx 

.  236  Japygia 
237  Solis  Promontorium 

276  Tyndis 
277  Oenotria 

197  Galaxias 

238  Aeolus 

278  Arsia  Silva 

198  Boreas 

239  Casuentus 

279  Palicorum  Lacus 

199  Achelous 

240  Hammonis  Cornu 

280  Nessonis  Lacus 

200  Aquae  Calidae 

241  Typhon 

281  Lausonius  Lacus 

201  Boreosyrtis 

242  Anubis 

282  Nuba  Lacus 

202  Lethes 

243  Asopus 

283  Mare  Icarium 

203  Amenthes 

244  Arosis 

284  Acheron 

204  Astapus 
205  Isidis  Kegio 
206  Nepenthes 

245  Astaboras 
246  Nilosyrtis 
247  Phison 

285  Mare  Erythraeum 
286  Ophir 
287  Ausonia 

207  Libya 

248  Sirbonis  Lacus 

288  Daphne 

208  Triton 

INDEX 


Age,  of  a  planet,  206  et  seq. ;  of 
Mars,  207. 

Air.     (See  Atmosphere.) 

Aphelion,  of  Mars'  orbit,  12. 

Apsides,  line  of  Martian,  22 ;  in- 
fluence on  Martian  seasons,  23. 

Aqueous  vapor,  49  ;  boiling 
point  of,  on  Mars,  59 ;  speed  of 
molecules  of,  Appendix,  Note  I. 

Araxes,  the,  change  in  shape  ac- 
counted for,  161. 

Areography,  92  et  seq. 

Atmosphere,  importance  of,  31 ; 
evidenced  by  change,  31 ;  ab- 
sence on  the  Moon,  32  ;  presence 
on  Mars,  32 ;  measured  on  Mars 
by  Mr.  Douglass,  37;  method 
of  determination  of,  38  ;  quan- 
tity of,  on  Mars,  43  ;  character- 
istics of,  on  Mars,  45;  veiling 
by,  48  ;  density  of,  on  Mars,  50, 
62,  75  ;  boiling  point  of  water 
in,  59;  constitution  of,  75;  in 
relation  to  seeing,  139 ;  spectro- 
scopic  observations  on  Martian, 
Appendix,  Note  III. 

Ausonia,  strait  between  it  and 
Hellas,  115. 

Autumn,  length  of  Martian,  24. 

Axis,  tilt  of  Martian,  22;  influ- 
ence on  Martian  seasons,  23. 

Band,  surrounding  polar  cap,  77  ; 

composition  of,  80. 
Beer  and  Madler,  on  north  polar 

cap,  78. 
Boreas,  the,  62. 


Bright    spots,  on  disk,  60,  61; 

variability  of,  62. 
Brilliancy,  relative,  of  Mars,  12. 
Brontes,  the,  133,  164. 

Calendar,  the  Martian,  77. 

Canals,  121,  128,  129  et  seq.  ; 
straightness  of,  131 ;  breadth  of, 
132 ;  length  of,  133,  134 ;  his- 
tory of,  136 ;  doubling  of,  137 ; 
duplication  of,  140,  187  et  seq. ; 
catalogue  of,  145;  number  of, 
147 ;  not  natural  features,  151, 
153;  changes  in,  155,  157, 161, 
162 ;  constitution  of,  164,  202 ; 
in  dark  regions,  97,  148,  171  et 
seq. ;  at  times  invisible,  155 ; 
list  of,  in  dark  regions,  173. 

Carbonic  acid  gas,  theory  of,  as 
related  to  polar  cap,  80 ;  char- 
acteristics of,  81;  objection  to 
theory  of,  83 ;  critical  veloc- 
ity of  molecules  of,  Appendix, 
Note  I. 

Carbonic  dioxide.  (See  Carbonic 
acid  gas.) 

Cassini,  rotation  of  Mars,  21. 

Causeways,  118. 

Ceraunius,  relative  visibility  of, 
183. 

Changes,  on  disk,  33,  34 ;  in  tint 
of  land  areas,  104,  110  et  seq., 
118;  in  canals,  155,  157,  161, 
162  ;  seasonal  and  secular,  161 ; 
in  spots,  182. 

Cimmerian  Sea.  (See  Mare  Ci'm- 
merium.) 


224 


INDEX 


Clerk-Maxwell,  determination  of 

molecular  speed,  54. 
Climate,  of  Mars,  49. 
Cloudlessness,  of  Martian  skies, 

45. 
Clouds,  45,  62  ;  how  formed,  52 ; 

as  seen  on  terminator,  64,  65; 

kinds,  68;  curious  example  of, 

seen  by  Mr.  Douglass,  70  et  seq. ; 

height  of  same,  73;  movement 

of  same,  74  ;  no  trace  of  veiling 

of  surface  by,  157. 
Color,  of  Mars,  121 ;  of  land  areas, 

177. 

Comet-tail  peninsulas,  103. 
Cooling,    of    the  Earth,    30;   of 

Mars,  30. 
Cracks,  theory  of  the  canals  as, 

152. 
Critical  velocity,  defined,  55  ;  of 

the  Earth,  56,  Appendix,  Note  I.; 

of  Mercury,  58,  Appendix,  Note 

I. ;  of  Mars,  58,  Appendix,  Note 

I. ;  of  Venus,  of  the  Moon,  of 

Jupiter,  of  Saturn,  of  Uranus,  of 

Neptune,  of  the  Sun,  Appendix, 

Note  I. 
Cyane  Fons,  relative  visibility  of, 

183. 

Dardanus,  the,  double,  196. 
Dark  areas,  depressions  over,  69. 
Day,  of  Mara,  22. 
Deimos,  orbit  and  size,  Appendix, 

Note  IV. 

Density,  of  Mars,  19. 
Denudation,     far    advanced     on 

Mars,  171,  207. 
Depressions,  on   terminator,  65; 

on  terminator,  over  dark  areas, 

69. 

Deserts,  of  Mars,  60, 108. 
Deucalionis  Regie,  neck  between 

it  and  Fastigium  Aryn,  118. 
Development,  seasonal,    in  seas, 

122 ;  of  canals,  154  et  seq.. 


Diameter,  of  Mars,  equatorial,  16, 
42 ;  polar,  42 ;  Appendix,  Note  II. 

Distance,  relative,  of  Mars  from 
Earth,  4, 12. 

Double  canals,  on  map,  106 ;  ac- 
count of,  188  et  seq. ;  appearance 
of,  189;  width  between,  190; 
manner  of  doubling,  190,  192. 

Douglass,  A.  E.,  measurement  of 
diameters,  41 ;  cloud  observa- 
tions, 70 ;  rift  in  polar  cap, 
87 ;  observations  on  the  Nectar, 
194. 

Duplication,  of  canals.  (See  Gem- 
ination.) 

Earth,  ellipticity  of  the,  25  ;  crit- 
cal  velocity  of  the,  56,  Appen- 
dix, Note  I. 

Eccentricity,  of  orbit  of  Mars,  24 ; 
of  the  Earth,  24. 

Elysium,  60,  61. 

Equator,  inclination  of  Martian, 
to  orbit,  77. 

Equinoxes,  77 ;  vernal  equinox  of 
Martian  southern  hemisphere, 
114 ;  autumnal  equinox  of  Mar- 
tian southern  hemisphere,  114. 

Eridania,  60. 

Eumenides,  length  of  the,  133; 
oases  detected  on  the,  181. 

Eunostos,  the,  62. 

Euphrates,  the,  shown  double, 
106;  doubling  of,  194. 

Faraday,  experiments  on  carbonic 
acid  gas,  81. 

Fastigium  Aryn,  the,  origin  of 
Martian  longitudes,  95 ;  neck  be- 
tween it  and  Deucalionis  Regio, 
118. 

Flammarion,  Camille,  "La  Pla- 
nete  Mars,"  111. 

Fons  Juventae,  the,  96,  180,  193. 

Frost,  possible  effect  of,  on  Mars, 


INDEX 


225 


Galaxias,  the,  62. 

Ganges,  the,  98  ;  length  of,  133 ; 

canals  near,  156;   double,  190, 

118,  194. 
Gases,  on  the  Earth,  50 ;  on  Mars, 

50  ;  effect  of,  on  atmosphere,  51. 
Gemination,  of  canals,  190  et  seq. 
Gigas,  oases  on  the,  182. 
Gihon,  name  of  the,  142. 
Glacial  epochs,  24. 
Glaciation  cracks,  theory  of  the 

canals  as,  152. 
Gorgon,  the,  164 
Gravitation,  law  of,  10. 
Gravity,  on  the  Earth,  19;  on  Mare, 

19 ;  effect  of,  on  atmosphere,  51. 
Green,  N.  E.,  observations  at  Ma- 
deira, 87 ;  map  of  Mars,  141. 
Gulf  of  the  Titans.     (See  -Sinus 

Titanum.) 

Hades,  the,  194. 

Hammonis  Cornu,  neck  between 

it  and  Hellas,  119. 
Heat,  on  Mars,  13;  inherent,  of 

Mars,  30. 
Hellas,  105  ;  strait  between  it  and 

Noachis,   115;  between  it   and 

Ausonia,  115 ;  neck  between  it 

and  Hammonis  Cornn,  119. 
Hesperia,  change  in,  116, 118. 
Hourglass  Sea,  the,  21. 
Huyghens,  drawing  of  Mars,  21. 
Hydrogen,  speed  of  molecules  of, 

54,  Appendix,  Note  L ;  in  free 

state,  56. 

Ice,  particles  of,  in  Martian  air,  49, 

82. 
Ice-cap.      (See    Polar    cap,    and 

South  polar  cap. ) 
Indus,  the,  first  seen,  157. 
Inhabitants,  of  Mars,   127,   128, 

204  et  seq. 
Irregularities,  on  terminator,  not 

mountainous,  66. 


Irrigation,  necessity  for,  128, 130; 

theory  of,  supported,  172,  202. 
Islands,  south  temperate  chain  of, 

115. 

Jupiter,  relative  orbit  and  size  of, 
5 ;  ellipticity  of  disk  of,  25  ;  ev- 
idence of  atmosphere  about,  57  ; 
discovery  of  satellites  of,  140; 
critical  velocity  of,  Appendix, 
NoteL 

Kepler,  laws  of  solar  system  of, 
10. 

Lake  of  the    Sun.     (See    Solis 

Lacus.) 

Lakes,  of  Mars,  184. 
La  Place,  theory  of  primal  nebula 

of,  4. 

"  La  Planete  Mars,"  111,  141. 
Libya,  105. 

Life,  extra-terrestrial,  5. 
Light,  on  Mars,  13. 
Limb,  of  Mara,  46. 
Limblight,  46. 
Linne,  32. 

Madler,  Beer  and,  on  north  polar 

cap,  78. 
Map,  of  Mars,  92  et  seq.,  141  et 

seq.,  and  at  end  of  Appendix. 
Maraldi,  study  of  polar  caps,  22. 
Mare  Cimmerium,  120. 
Mare  Erythraeum,  120. 
Markings,   a  peculiarity  of   the 

Martian,  123,  124  ;  bluish-green, 

108,    133;    reddish-ochre,    108, 

133. 
Mars,    passim.      (See    particular 

headings.) 
Martian  life,  202. 
Martians,  as  different  from  men, 

204  ;  probability  of,  209  et  seq. 
Mass,  of  Mars,  how  determined, 

16. 


226 


INDEX 


Matter,  as  common  property,  4. 

Memnonia,  60. 

Mercator,  map  of  Mars  on  projec- 
tion, 143,  and  after  Appendix. 

Mercury,  ellipticity  of  disk  of,  25 ; 
evidence  of  atmosphere  about, 
57 ;  cusps  of,  57  ;  critical  veloc- 
ity of,  58,  Appendix,  Note  I. 

Meteorites,  theory  of  canals  as 
made  by,  152. 

Micrometric  measures,  of  diam- 
eters, by  Mr.  Douglass,  27. 

Mind,  universality  of,  4. 

Mist,  sunrise,  46 ;  sunset,  46,  157. 

Mitchell  Mountains,  87. 

Molecules,  kinetic  theory  of, 
53;  speed  of,  54,  Appendix, 
Note  I. 

Moon,  cosmically  dead,  2;  rela- 
tive orbit  and  size  of,  4 ;  changes 
on,  32  ;  atmosphere  of,  57. 

Mountains,  66 ;  how  detected  on 
a  planet,  43  ;  as  seen  on  termi- 
nator, 48,  69, 167  et  seq. 

Names,  of  planets,  207. 

Nectar,  the,  99  ;  double,  194. 

Neptune,  relative  orbit  and  size 
of,  5 ;  probable  elliptieity  of  disk 
of,  25  ;  evidence  of  atmosphere 
about,  57;  critical  velocity  of, 
Appendix,  Note  I. 

Newton,  law  of  gravitation,  10. 

Nice,  observatory  of,  138. 

Night,  on  Mars,  19. 

Nitrogen,  speed  of  molecules  of, 
57,  Appendix,  Note  I. 

Noachis,  strait  between  it  and 
Hellas,  115. 

Nomenclature,  of  Martian  mark- 
ings, 94,  95,  141,  142 ;  meaning 
of  Schiaparelli's,  142. 

Oases,  131,  176  et  seq. ;  shape 
of,  178,  187  ;  size  of,  179 ;  onEu- 
nieaides-Orcus,  181;  on  Pyri- 


phlegethon,  182 ;  on  Gigas,  182. 

(See  Spots.) 
Ophir,  60. 

Opposition,  of  Mars,  13. 
Orbit,  of  Mars,  8  ;  compared  to  the 

Earth's,  10  ;  eccentricity  of,  24. 
Oxygen,  speed  of  molecules  of,  53, 

Appendix,  Note  I. ;  in  free  state, 

57. 

Parabolic  velocity,  55. 

Pearl-bearing  Gulf,  the,  96,  156. 

Peninsulas,  comet-tail,  103. 

Perihelion,  of  orbit  of  Mars,  11. 

Perrotin,  detection  of  the  Phison, 
137,  138 ;  confirmation  of  canals 
of  Schiaparelli,  138. 

Phase,  of  Mars,  19,  37,  46. 

Phasis,  the,  161. 

Phison,  the,  shown  double,  106 ; 
name  of,  142  ;  double,  190 ;  dou- 
bling of,  195. 

Phobos,  orbit  and  size  of,  Appen- 
dix, Note  IV. 

Phoenix  Lake,  the,  99,  100,  133 ; 
canals  near,  162 ;  relative  con- 
spicuousness  of,  183 ;  polari- 
scopic  observation  of,  185. 

Photography,  of  planet,  93. 

Pickering,  Prof.  W.  H.,  estimate 
of  height  of  cloud,  71 ;  polari- 
scope  observations,  80,  185 ;  ob- 
servations of  rift  in  polar  cap, 
85  ;  an  open  polar  sea,  88,  175 ; 
120 ;  names  by,  141. 

Planets,  name  of,  1 ;  relative  orbits 
and  sizes  of,  4,  5 ;  as  wandering 
stars,  9  ;  as  a  solar  family,  10. 

Polar  caps,  22,  33, 76.    (See  South 

polar  cap.) 

Polar  flattening,  25,  27  ;  amount 
of,  42. 

Polariscope,  observations  on  polar 
sea,  80;  on  so-called  seas,  109, 
120 ;  on  the  Solis  Lacus  and  the 
Phoenix  Lake,  185. 


INDEX 


227 


Polar  sea,  79  et  seq.,  92,  114,  119. 

Polar  snows,  relation  of,  to  sur- 
face activity,  113. 

Pole,  south,  of  cold  not  coincident 
with  pole  of  rotation,  85. 

Poles,  of  Mars,  tilt  of,  22. 

Presentation,  meaning  of,  note, 
156. 

Proctor,  map  of  Mars,  141. 

Projections,  on  terminator  of 
Mars,  63,  64. 

Protei  Regio,  72. 

Psychic  effect,  on  seeing,  158- 
160. 

Pyriphlegethon,  the,  oases  de- 
tected on,  182. 

Rifts,  in  south  polar  cap,  85,  87. 

Rotation,  of  Mars,  time  of,  21,22, 
95, 107. 

Satellites,    of    Mars,    Appendix, 

Note  IV. 
Saturn,  relative  orbit  and  size  of, 

5 ;  critical  velocity  of,  Appen- 
dix, Note  I. 
Schiaparelli,  on  tilt  of  Martian 

poles,   77;  map   of    Mars,  94; 

first  detection  of  canals,  136  et 

seq. 

Sea  of  the  Sirens,  the,  120. 
Seas,  of  Mars,  so  called,  96,  107 

et  seq.,  123,  126,  127 ;  variation 

in  tint  of,  110,  118,  120 ;  of  the 

Moon,  123. 
Seasons,  of  Mars,  23 ;  length  of, 

24  ;  phenomenally  hot  season  in 

southern   hemisphere   of    Mars, 

91. 
Seeing,  conditions  conducive  to, 

138,  139. 

Shape,  of  Mars,  14  ;  of  oases,  179. 
Sinus  Titanum,  101,  134;  canals 

near,  156,  182. 

Size,  of  Mars,  14  ;  of  oases,  179. 
Snow,  on  Mars,  33. 
Snow-caps.  (See  South  polar  cap.) 


Solar  system,  size  of  the,  4,  14, 
15. 

Soils  Lacus,  99 ;  canals  near,  155 ; 
size  of,  180 ;  polariscope  obser- 
vations on,  185;  bright  cause- 
ways in,  194. 

Solstices,  of  Mars,  77;  summer 
solstice  of  southern  hemisphere, 
114. 

Southern  hemisphere,  of  Mars, 
seasons  in,  24  ;  terminator  of,  64. 

South  polar  cap,  irradiation  from, 
27 ;  dwindling  of,  33 ;  size  of,  in 
June,  76 ;  disappearance  of,  79, 
90 ;  constitution  of,  80,  83,  94 ; 
history  of,  84  et  seq.;  eccen- 
tricity of,  85;  rift  in,  85,  87; 
starlike  points  in,  86,  87 ;  de- 
tached portions  of,  89  ;  different 
levels  of,  89  ;  disappearance  of, 
90. 

South  polar  sea,  94. 

South  pole,  of  cold  on  Mars  not 
coincident  with  geographical 
pole,  85. 

Spectroscope,  observations  on 
stars,  4  ;  observations  of  atmos- 
phere of  Mars  by,  Appendix  III. 

Spots,  in  bright  areas  (see  Oases) ; 
on  border  of  dark  areas,  197 ;  as 
terminals  to  canals,  197 ;  in  dark 
areas,  198 ;  list  of ,  199. 

Spring,  length  of,  on  Mars,  24. 

Stars,  Mars  as  one,  1;  relative 
distance  of,  5. 

Stoney,  G.  Johnstone,  53. 

Storms,  on  Mars,  59. 

Straits,  in  dark  areas,  114,  115, 
117,  168,  173. 

Struve,  Hermann,  29. 

Summer,  length  of.  on  Mars,  24. 

Sun,  relative  size  of,  4  ;  effect  on 
planet's  age,  206. 

Surface,  of  Mars,  features  of, 
93. 

Syrtis  Major,  20,  105,  119, 141. 


228 


INDEX 


Tempo,  60. 

Terminator,  observations  on,  48, 
63,  64 ;  irregularities  on,  63 ;  of 
Moon,  169;  of  Mars,  170. 

Tisserand,  on  polar  flattening  of 


Titan,  the,  102,  134,  164. 
Tithonius  Lacus,  99,  181. 
Trivium     Charontis,    103,    133, 

181 ;  shape  of,  179. 
Twilight,  on  Mars,  measured  by 

Mr.  Douglass,  26. 
Twilight  arc,  of  Mars,  42. 
Typhon,  the,  double,  195. 

Uranus,  relative  orbit  and  size  of, 
5  ;  ellipticity  of  disk  of,  25  ;  evi- 
dence of  atmosphere  of,  57 ;  crit- 
ical velocity  of,  Appendix, 
Note  I. 


Variations,  of  surface  of  Mars. 
(See  Changes.) 

Vegetation,  on  Mars,  122, 164 ;  vis- 
ibility of,  130, 198. 

Velocity,  critical,  of  planets,  Ap- 
pendix, Note  I. 

Venus,  cloud-covered,  2;  ellipti- 
city of  disk  of,  25  ;  evidence  of 
atmosphere  of,  57  ;  cusps  of,  57 ; 
critical  velocity  of,  Appendix, 
Note  I. 

Water,  79,  83,  92 ;  necessary  to 
life,  76,  127 ;  theoretic  reflection 
from,  109  ;  amount  of,  on  Mars, 
122  ;  direction  of,  when  flowing 
from  pole,  125 ;  as  fresh,  175. 

Weather,  on  Mars,  58. 

Winter,  length  of,  on  Mars,  24. 

Worlds,  other  than  our  own,  3. 


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